Showing papers in "Transactions of the Japan Society of Mechanical Engineers. C in 2001"
TL;DR: The design and characteristics of the power assisting suit using the cuff type pneumatic rotary actuators and the muscle hardness sensor verifying its practicability are given.
Abstract: In order to realize a power assisting suit for assisting a nurse caring a patient is her arm, a hardness sensor of muscle using load cell and a pneumatic rotary actuator utilizing pressure cuffs have been developed The power assisting suit consists of shoulders, arms waist and legs made of aluminum, and is fitted on the nurse body The power assisting suit was originated with the concept of a master and slave system in one body The arms, waist and legs have the pneumatic rotary actuators The pneumatic rotary actuators construct with pressure cuffs sandwiched between thin plates The action of the arms, waist and legs of the nurse were sensed with the muscle hardness sensor utilizing load cell with diaphragm mounted a sensing tip The dent of the sensing tip corresponds to the hardness of the muscle so that exerting muscle force produces electric signal This paper gives the design and characteristics of the power assisting suit using the cuff type pneumatic rotary actuators and the muscle hardness sensor verifying its practicability
21 citations
TL;DR: The robust hyper plane that is frequencyshaped by H infinity control is applied and it is proposed that this system could succeed in reducing not only the chattering of output (engine speed) but also the chatter of control input while keeping the high performance.
Abstract: The idle speed reduction is one of the important solutions for fuel economy improvement. And to achieve it, it is required to improve the performance of idle speed control to prevent from engine stall. We consider that the sliding mode control (SMC) representative in the nonlinear control theory is suitable for the idle speed control system. Because this system has non linearity like torque and friction characteristics. However it was said that it was difficult to get the high performance by SMC because of the chattering problem. In the previous paper, we described the following issues. The chattering problem comes from the large switching gain to attenuate the disturbance that does not satisfy the matching condition. However we could reduce the chattering of output (engine speed) by applying the acceleration reaching law and we could get the high performance superior to PID and LQG. In this paper, we describe the more effective way to reduce the chattering. That is, we applied the robust hyper plane that is frequencyshaped by H infinity control. And then we could succeed in reducing not only the chattering of output (engine speed) but also the chattering of control input while keeping the high performance.
18 citations
17 citations
TL;DR: In this paper, the authors examined numerical analysis of particle velocity and temperature distribution of struck material surface in fine particle peening and calculated the velocity of a 50 μm particle, just before striking the metal surface.
Abstract: This study examines numerical analysis of particle velocity and temperature distribution of struck material surface in fine particle peening. When the particle is accelerated using a direct-pressure type, the velocity of a 50 μm particle, just before striking the metal surface, was calculated to be 222 m/s. In applying air pressure, the acceleration of fine particles show significant increase compared to larger sizes. Moreover, the experimental values agree well with the calculated ones. On the other hand, the temperature distributions show the maximum surface temperature to be 1500 K and cools instantly.
16 citations
TL;DR: In this article, a closed-form exact solution for the H2 optimization of DVAs attached to the damped primary systems is proposed, where the primary system is subjected to random excitation instead of sinusoidal one.
Abstract: The objective of the H2 optimization of the dynamic vibration absorbers (DVAs) is to minimize the vibration energy transmitted to the system from the source of excitation. In this optimization criterion, the squared area (called H2-norm) under the frequency response curve of the system is minimized. If the system is subjected to random excitation instead of sinusoidal one, then the H2 optimization is probably desirable than the popular H∞ optimization. The H2 optimization is a classical optimization problem of DVAs, and has been already solved for a special case when the primary system has no damping. However, for the general case where the damping is present in the primary system, the H2 optimization problem is not solved by algebraic approach until today. This paper proposes a closed-form exact solution for the H2 optimization of DVAs attached to the damped primary systems.
16 citations
TL;DR: In this paper, a sliding mode controller based on the theory of model following control for semi-active suspension systems with Magnetorheological (MR) dampers which have undesirable nonlinear properties is presented.
Abstract: This paper presents a new sliding mode controller based on the theory of model following control for semi-active suspension systems with Magnetorheological (MR) dampers which have undesirable nonlinear properties. In the proposed controller, a desired semi-active suspension system is chosen as the reference model to be followed, and the control low is determined so that an asymptotically stable sliding mode will occur in the error dynamics between the plant and the reference model states. The advantages of the proposed controller are : (1) measurement of the damping force is not required, (2) the reference model specifies the desired performance considering the passivity constraint of the damper, (3) it is highly possible to maintain the sliding mode and achieve high robustness against the nonlinear properties of the damper. Numerical simulations illustrate the effectiveness of the controller.
15 citations
TL;DR: In this paper, a design method for vibration isolation control of a semi-active suspension for automobiles is proposed, which takes account of mechanical constraints such as valve stroke and damping coefficient restriction, and the gain-scheduled controller based on linear matrix inequalities is obtained so that the closed-loop system may be stable and have good performance even if saturation of the valve stroke occurs.
Abstract: This paper proposes a design method for vibration isolation control of a semi active suspension for automobiles. By using nonlinear functions we formulate the linear-parameter-varying system taking account of mechanical constraints such as valve stroke of the semi-active damper and the damping coefficient restriction. The gain-scheduled controller based on the linear matrix inequalities is obtained so that the closed-loop system may be stable and have good performance even if saturation of the valve stroke occurs. By simulations it is verified that the semi-active damper system designed is effective in comparison with either a passive damper or a conventional switching law based on H∞ control.
14 citations
TL;DR: In this paper, a bilinear optimal control theory is established by adopting the damping force in criteria function and it is applied to a semi-active base isolation problem, where the authors deal with 10 stories structure model corresponding to an actual building and the dynamics of an oil damper is taken into consideration by using the Maxwell model in the modelling.
Abstract: In vibration isolation control problem, semi-active control methods in which coefficient of viscous damping or spring constant are varied effectively have been proposed and expected to realize a high performance with a little energy consumption However, the semi-active system is classified into a bilinear system which belongs to a nonlinear system and its controller design is not easy In this study, a bilinear optimal control theory is established by adopting the damping force in criteria function and it is applied to a semi-active base isolation problem This study deals with 10 stories structure model corresponding to an actual building and the dynamics of an oil damper is taken into consideration by using the Maxwell model in the modelling Moreover, the dynamics of disturbance is taken into account, and the controller is designed for the augmented bilinear system which includes both the control object and the disturbance And the computer simulation is carried out by taking account of the delay to switch the coefficient of dampers in order to compare the performance on semi-active base isolation controls designed by the proposed method with skyhook control method and passive isolations As a result, the usefulness of the present method was demonstrated
14 citations
TL;DR: In this article, the effects of the normal load between two rollers, the back tension of a paper sheet and also the change of the frictional coefficient on the velocity ratios of the paper translation to the roller rotation are investigated.
Abstract: Paper feeding systems with rubber-covered roller drive are widely used in information processing devices such as copy machines, printers and ATM. It is important in their designs to control the paper velocity with precision. Accordingly, the experimental verification is carried out to estimate the effects of the normal load between two rollers, the back tension of a paper sheet and also the change of the frictional coefficient on the velocity ratios of the paper translation to the roller rotation. Next, the behaviors of a rubber-covered roller driving a loaded paper sheet together with a rigid roller are simulated in transition from the micro-slip contact to the rolling contact with non-linear finite element analyses. And furthermore, the variations of the shearing stress distributions and the deformations of the rubber as well as the local slippage in the various kinds of conditions are investigated by enforcing the rotating condition on the rubber-covered roller. As a result, the effects of the normall load, the tension force and the driving configuration on the velocity ratios are studied by using the presented mechanical model, which is based on the deformation mode and the micro-slip zone in the contact nip.
11 citations
TL;DR: In this article, a motion control that stabilizes the pendulum to a desired limit cycle by a periodic input is presented, which is consisted of a periodic solution of van der Pol's equation.
Abstract: Periodic input sometimes controls mechanical systems dynamically. We have investigated a pendulum system from a view point of such a dynamic control. In this paper, we present the motion control that stabilizes the pendulum to a desired limit cycle by a periodic input. In our method, the periodic input is added so that the energy of the pendulum may become the energy of the desired limit cycle, and is consisted of a periodic solution of van der Pol's equation which is inputted the angle of the pendulum. Experimental results support the effectiveness of the proposed method.
11 citations
TL;DR: In this article, the experimental results of the squeal of disk brake of floating type were described and a coupled vibration mode between rotor and caliper through pads was found. But it was not shown that the frequency of the noise changes according to the contact distribution in the circumferential and the radial directions between the rotor and pads.
Abstract: This paper describes the experimental results of squeal of disk brake of floating type. The squeal of new type has a low frequency and a coupled vibration mode between rotor and caliper through pads. From the experiments, it was made clear that the occurrence of the squeal changes according to the contact distribution in the circumferential and the radial directions between rotor and pads. In the case of cutting a part of pad surfaces in the circumferential direction, it is effective for squeal reduction to cut the pointed end pad surfaces of leading side on the inner side, and in the case of cutting a part of pad surfaces in the radial direction, it is effective for squeal reduction to cut outer pad surfaces of inside in the radial direction. Moreover, frictional vibration of a block subjected to distributed friction at contact surface was treated analytically and experimentally and a common mechanism of vibration of block and disk brake was found.
TL;DR: In this article, a method of measuring contact points of running railway vehicles is proposed and evaluated by improving conventional methods of measuring wheel load and lateral force on disk type wheelset, under the conditions that vertical, lateral and longitudinal forces act separately on various points along the wheel profile.
Abstract: In this paper, a method of measuring contact points of running railway vehicles is proposed and evaluated. The new method is developed by improving conventional method of measuring wheel load and lateral force. Firstly, surface strain on disk type wheel is analyzed by FEM under the conditions that vertical, lateral and longitudinal force acts separately on various points along the wheel profile. The calculated result shows possibility of detecting rail/wheel contact point by means of measuring lateral distribution of compress strain which changes according to the load position i.e. rail/wheel contact point. Secondly, this idea is verified by static load experiments using an actual disk type wheelset. The location of an area where lateral force affects little on surface strain is investigated, since the lateral distribution of strain should be measured in such an area to avoid the interference of disk bend by lateral force. Finally, the theory for the measurement is modified for on-track testing.
TL;DR: In this paper, a design assessment method for the product definition of a new product, which is an essential key toward market success of consumer products under the today's rapid and competitive product cycle, based on existing products along with such life stages.
Abstract: Every kind of consumer products is deployed from market-in stage through growing-up stage to maturated stage by gradually shifting its appealing features from fundamental functions to supplemental value-addition over its life stages. This paper proposes a design assessment method for the product definition of a new product, which is an essential key toward market success of consumer products under the today's rapid and competitive product cycle, based on existing products along with such life stages. Since a series of products over life stages share the underlying design concepts, the contents of their quality-function-deployment tables must be partially shared with each other, while the definition of customer attributes is shifted due to their growth and maturation in market. Based on this observation, an assessment method is organized based on quality function deployment and cost-worth graph to facilitate establishment of product definition. Its validity and promise is ascertained through analyzing design changes across three vacuum cleaners in different life stages.
TL;DR: In this article, a series of experiments was performed in a low temperature environment in order to suppress the evaporation of fluid while realizing a large temperature difference between the both ends of the bridge to attain a high Marangoni number in spite of a small size of a bridge.
Abstract: 河村 洋,小野 嘉久,上野 一郎 Transition and Modal Structure of Oscillatory Marangoni Convection in Liquid Bridge Hiroshi KAWAMURA, Yoshihisa ONO and Ichiro UENO Dept. Mech. Eng., Fac. Sci. & Tech., Science University of Tokyo, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan A large number of terrestrial experiments have been conducted on Marangoni convection in a liquid bridge to date. The limitation in the terrestrial experiments lies in the maximum size of the bridge and thus in the maximum attainable Marangoni number in normal gravity. In the present study, a series of experiments was performed in a low temperature environment in order to suppress the evaporation of fluid while realizing a large temperature difference between the both ends of the bridge to attain a high Marangoni number in spite of a small size of the bridge. The test fluid was silicone oil of 1, 2 and 5 cSt. The temperature difference ∆T was increased gradually and a critical point of transition from steady to oscillatory flow was obtained. With increase of ∆T, a pulsative oscillatory mode and then a rotational one became discernable. In this series of experiments a wide range of aspect ratio of the bridge was concerned and thus flow structures with mode number m = 1, 4, 5 and 6 were realized. The product of the mode number and the aspect ratio was found to be approximately unity as often pointed out.
TL;DR: In this article, the authors present a practical and quantitative technique for assessment and localization of infancy damages in a structure by measuring the impedance change of piezoelectric patches which were glued on the structure.
Abstract: This paper presents a practical and quantitative technique for assessment and localization of infancy damages in a structure by measuring the impedance change of piezoelectric patches which were glued on the structure. The consideration of longitudinal wave propagation in structures is introduced for quantitative assessment of damage characteristics because the corresponding frequency regions are easily determined with longitudinal wave propagation analysis. It is shown that the damage location can be simply estimated by measuring the PZT's electric impedance and comparing with the longitudinal strain mode shape functions in the healthy structure.
TL;DR: A neuro-musculo-skeletal model is constructed that can spontaneously generate natural reaching motion without priorly forming trajectory, suggesting that the proposed neural mechanism may be incorporated into actual human motor control.
Abstract: A neuro-musculo-skeletal model is constructed that can spontaneously generate natural reaching motion without priorly forming trajectory. The musculo-skeletal structure of human upper extremity is modeled as three rigid links with eight muscles. A visco-elastic element is attached around each joint to represent passive joint structure. The nervous system is modeled as a recurrent neural network which incorporates a potential defining body mobility due to the anatomical constraints, with a spatial potential defining a goal position. Given a goal position, the nervous system autonomously generates muscular activation signals that tend to move the hand to the goal. Due to the dynamic interaction among the entire neuro-musculo-skeletal systems, motion is naturally induced from the anatomical constraints. The simulated motions agree with those of humans, suggesting that the proposed neural mechanism may be incorporated into actual human motor control.
TL;DR: In this article, a hybrid actuator using five electromagnets and thirty permanent magnets is proposed to stabilize the elastic vibration of a rectangular sheet steel and increase the damping factor of elastic vibration.
Abstract: This paper proposes a levitation control device for a rectangular sheet steel by the hybrid actuator using five electromagnets and thirty permanent magnets. The five electromagnets are independently controlled by feedback signals from gap sensors to stabilize a levitation behavior. The thirty permanent magnets are installed to support the static deflection of the sheet steel. In addition, it is found that the permanent magnets increase the damping factor of elastic vibration and work effectively for the electromagnetic levitation. In this study, the attractive force of the permanent magnets is analyzed by using the finite element method and the elastic vibration of the sheet steel is calculated by the finite difference method. To verify usefulness of the proposed levitation control system, an experiment applying the digital optimal control theory was performed for the rectangular sheet steel (length: 800 mm, width: 600 mm, thickness: 0.3 mm). As a result, in comparison with the system only using the electromagnets, it was confirmed that the control performance was improved by using the permanent magnets.
TL;DR: In this article, the modal analysis is applied to the stability analysis of a large-scale nonlinear structure to reduce the dimensions of the structure without the decrease of accuracy, and two modal matrices are considered in the reduction of dimension, and the method is proposed to select rationally the modes that dominate the stability of the solution.
Abstract: By applying the incremental transfer stiffness coefficient method suggested in the previous report to a large-scale nonlinear structure, the stable and unstable solutions can be computed without distinction. Therefore, the stability of the solution obtained has to be analyzed. It is, however, very difficult to analyze the stability of the solution of the large-scale nonlinear structure. In order to overcome the difficulty, the method to reduce the dimensions of the structure without the decrease of accuracy is developed by applying the concept of the modal analysis to the stability analysis of the variational equation. Two types of modal matrices are considered in the reduction of dimension, and the method is proposed to select rationally the modes that dominate the stability of the solution. The validity of the incremental transfer stiffness coefficient method and the method of stability analysis using reduction model is confirmed by the numerical computational results.
TL;DR: In this article, the negotiation process in virtual enterprise formulation is focused as a basic study to clarify its effective management, and a computer simulation model to form a virtual enterprise through multiple negotiations amongst several potential members in the negotiation domain, and clarify the negotiation dynamism in the virtual enterprise formation.
Abstract: Virtual enterprise is a temporary alliance of enterprises that come together to share skills, core competencies or resources. Each enterprise forming a virtual enterprise has to select appropriate business partners to realize profitable management with eliminating the risk. In this paper, the negotiation process in virtual enterprise formulation is focused as a basic study to clarify its effective management. We develop a computer simulation model to form a virtual enterprise through multiple negotiations amongst several potential members in the negotiation domain, and clarify the negotiation dynamism in the virtual enterprise formation.
TL;DR: In this article, singular dynamic phenomena were observed in a pin-to-plate gas discharge system, where the axial stiffness of a support of the pin electrode was low and the applied voltage was transiently decreased and then relaxed after the occurrence of the spark discharge and alternative force was induced due to alternative ionic wind.
Abstract: Some kinds of singular dynamic phenomena were observed in a pin-to-plate gas discharge system. (1) One was vibration of the pin electrode perpendicular to the plate electrode observed at the transition from the dark discharge and the positive corona discharge due to the streamer corona when the axial stiffness of a support of the pin electrode was low. Similar vibration was observed in the negative corona discharge due to Trichel pulse and instability of the negative corona. Both vibrations were the forced vibration due to pulsative or fluctuating electrostatic force caused by ionic wind at corona discharging. (2) Another axial vibration was observed at spark discharge for the softly supported pin electrode. The applied voltage was transiently decreased and then relaxed after the occurrence of the spark discharge and alternative force was induced due to alternative ionic wind. Thus a large forced vibration coupled with the intermittent spark discharge took place. (3) Lateral whirling of the pin electrode was observed at corona discharging when the pin electrode was extremely fine. Whirling frequency was increased with the increase of the applied voltage. Axial repulsive force due to the ionic wind was the cause of the whirling.
TL;DR: In this article, a numerical simulation of crack initiation and propagation in a blanking process of a steel sheet is done using rigid plastic finite element code developed by the authors, where the modified Cockcroft and Latham expression is used as a ductile fracture criterion and is linked with the simulation.
Abstract: Numerical simulation of crack initiation and propagation in a blanking process of a steel sheet is done using rigid plastic finite element code developed by the authors. The modified Cockcroft and Latham expression is used as a ductile fracture criterion and is linked with the simulation. It is assumed that when the fracture threshold is satisfied at an element, a crack occurs and propagates through the element. The node separate method is proposed as a method for simulating the crack propagation. To confirm the results of finite element simulation, blanking experiments are also carried out under various conditions, and the crack propagation with punch penetration and the shape of cut edge are observed. The experimental results show good agreement with those of the simulation.
TL;DR: In this article, an analytical model coupled between rotor and caliper through pads was presented to analyze the low frequency squeal of floating type disk brake, and the analytical results were compared with the experimental ones shown in the previous report.
Abstract: This paper presents an analytical model coupled between rotor and caliper through pads to analyze the low frequency squeal of floating type disk brake, and describes the analytical results, compared with the experimental ones shown in the previous report. From the analysis, it was made clear that the squeal changes according to the contact distribution in the circumferential and the radial directions between rotor and pads, that is, in the case of cutting a part of pad surfaces in the circumferential direction, it is effective for squeal reduction to cut the pointed end pad surfaces of leading side on the inner side, and in the case of cutting a part of pad surfaces in the radial direction, it is effective for squeal reduction to cut outer pad surfaces of inside in the radial direction. It was confirmed that these analytical results were in a fine agreement with the experimental ones.
TL;DR: In this paper, the effects of the natural frequencies of ball and head on the performance of a superior club head with high restitution performance were investigated by using the lumped mass models of balls and heads.
Abstract: In this paper, the effects of the natural frequencies of ball and head are investigated on the restitution performance in order to develop a superior club head with high restitution performance. Firstly, the coefficient of restitution is calculated by using the lumped mass models of ball and head. As a result, the coefficient of restitution increases when the natural frequencies of ball and head where the contact part is fixed or free, coincide with each other. And the coefficient of restitution is bigger when the natural frequencies of ball and head where the contact part is fixed, coincide with each other than when the natural frequencies of ball and head where the contact part is free, coincide with each other. Next, the ball and head are modeled by three-dimensional models and the release velocity of ball after impact is calculated. As a result, the maximum release velocity of ball can be obtained when the natural frequencies of ball and head where the contact part is fixed, coincide with each other.
TL;DR: In this paper, the authors presented new compact folding/wrapping patterns of flat circular membranes facilely deployable, which have been concerned with the design of a solar sail in space.
Abstract: The purpose of this paper is to present new compact folding/wrapping patterns of flat circular membranes facilely deployable, which have been concerned with the design of a solar sail in space. By modelling folding patterns with the help of origami concept, 3 kinds of new folding patterns in radial/circumferential directions have been developed by using 1 node with 4 folding lines. Well-known wrapping method around central hub has been also generalized, and other folding patterns consisting of repeating type of archimedean spiral arrangements have been newly devised based on the patterns developed by Guest et al.
TL;DR: A model of the shape of snail's sole section is proposed which will have a possibility to be applied to the mobility equipment which has flexibility for ground conditions and can easily turn in a house.
Abstract: This paper presents a study of the relationship between the contraction on the sole surface, the shape and the forces generated by muscle for locomotion of snail (Gastropod). We observed sole surface of a moving snail to investigate the state of contraction when a sole wave is passing. Then we measured the vertical and horizontal forces generated by sole to investigate the relationship between the forces and the shape of sole surface. Based on these results observed, we proposed a model of the shape of snail's sole section. The mechanism of snail's locomotion will have a possibility to be applied to the mobility equipment which has flexibility for ground conditions and can easily turn in a house.
TL;DR: In this article, a design method of neural controllers for semi-active suspensions with nonlinear devices such as electrotheological or magnetotheological dampers is presented, and two learning methods, the feedforward learning and the recurrent learning, for the controller are investigated from a viewpoint of system identification theories.
Abstract: This paper presents a design method of neural controllers for semi-active suspensions with nonlinear devices such as electrotheological or magnetotheological dampers. It is shown that the use of two neural networks corresponding to each signs of the relative velocity is effective to realize the desired controllers, i. e., semi active controllers inherently include discontinuous mappings due to the passivity constraint and it is generally very difficult to realize them with single neural network. A model-following type controller with these neural networks is proposed, and two learning methods, the feedforward learning and the recurrent learning, for the controller are investigated from a viewpoint of system identification theories : the equation error method and the output error method.