日本機械学会論文集
Online ISSN : 2187-9761
ISSN-L : 2187-9761
最新号
選択された号の論文の14件中1~14を表示しています
熱工学,内燃機関,動力エネルギーシステム
機械力学,計測,自動制御,ロボティクス,メカトロニクス
  • 荒木 清宏, Diego PAEZ-GRANADOS, Modar HASSAN, 鈴木 健嗣
    2024 年 90 巻 931 号 p. 23-00208
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/03/15
    ジャーナル オープンアクセス

    Soft robotics technology has the potential for a wide range of applications; however, their implementation is hindered by the lack of accurate mathematical models and control methods. For example, a method to control multiple pneumatic inflatable actuators in turn by a passive mechanism has been proposed in a literature, but no mathematical model was presented to develop control laws for the system. This study proposes a mathematical model for the inflation characteristics of sequential soft actuators, and theoretical control law for passive sequential control of the inflation of multiple actuators by using flow resistors. The model is constructed from the physical requirements of the actuators based on fluid dynamics and thermodynamics. The study shows that the pressure change characteristics can be derived from the differential equations even for complex parallel and series circuits. The model mathematically represents the physical principle by which the actuators' inflation order depends on the relationship between changes in the input pressure and internal pressure with time. Experiments with real circuits of simple and complex layouts are presented. The actuators are inflated in sequence from a single air pressure source, and the mathematical model was able to describe the pressure and flow rate change characteristics at each point in the circuit.

  • 橋本 大輝, 柴田 曉秀, 橋本 和紀, 堀金 智貴, 長畑 雄也, 東森 充
    2024 年 90 巻 931 号 p. 23-00248
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/03/15
    ジャーナル オープンアクセス

    This paper discusses the design of the mechanism for an artificial mastication device that reproduces the formation of the food bolus by humans. A novel mechanism, the enclosure area expansion and reduction mechanism, that can gather fragments of food is proposed. In the proposed mechanism, multiple movable walls with common shape and sizes form a symmetrical enclosure area that contains the food fragments. Driven by a single actuator, all walls move coordinately so that the enclosure area reduces and expands for gathering the fragments. We first show the mathematical formulation of the geometrical conditions of the movable walls. We then design the movable walls and power transmission system for a prototype installed in the artificial mastication device. Finally, we present the experimental results, which validate the proposed method.

  • 勝野 遥翔, 松村 雄一, 北原 篤, 石原 大雅
    2024 年 90 巻 931 号 p. 23-00255
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/28
    ジャーナル オープンアクセス

    This paper addresses a method for devising an undamped periodic structure that suppresses energy propagation due to a specific wave mode based on the Wave and Finite Element (WFE) method. Then, structural modifications to reduce the active transmitted power are derived by solving an inverse eigenvalue problem of the WFE method. In solving the inverse problem, it is important that the solution is feasible in the sense that it is low-cost and easy to fabricate as an actual mechanical structure. Therefore, in the proposed method, the designer specifies the regions in which structural modifications may be made before solving the inverse problem. As a result, the solution of the inverse problem is approximated within these regions. Finally, the method allows us to suggest feasible structural modifications necessary to reduce the amount of active transmitted power for a given wave mode and a given frequency. However, this method cannot consider the changes in wave numbers due to structural modification. It should therefore be noted that this method cannot be used to achieve significant reductions in active transmitted power due to large-scale structural modification.

  • 稻葉 雅至, 松村 雄一
    2024 年 90 巻 931 号 p. 23-00261
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/28
    ジャーナル オープンアクセス

    Vibration performance is the one of the important performances in automotive product because of related to not only ride comfort and control performance of vehicle but also durability and noise performance. However, it is difficult to design efficiently because the performance is determined by the influence of all components constituting of a whole structure. In previous paper, we presented an effective way to design vibration performance based on an inverse method for structural modification that keeps one specified eigenfrequency and its eigen vector of the whole structure the same. In this paper, we propose a new method to keep the specified multiple eigenfrequencies and their eigen vectors the same. Firstly, the matrices for structural modification are calculated as dynamic stiffness matrix variation from the zero-divisors of the specified multiple eigen vectors. The design of dynamic stiffness matrix variation is simplified by representing the matrix variation as just stiffness matrix variation which is independence on eigen frequency. Furthermore, it is possible to represent the calculated matrices redundantly by using an arbitrary non-zero weighting matrix. However, the matrices are generally calculated as fully populated and non-symmetric matrices. Therefore, secondly, we transform the matrices calculated as the zero-divisors into the sparse matrix of reduced row echelon form in advance. This transformation simplifies building symmetric and sparse matrices for realizable structural modification. This sparse matrix, redundantly represented by a weighting matrix, allows a value analysis to select among alternative structural changes to simplify structural complexity while keeping several performances originated from vibration performance. Finally, the proposed method was applied to a numerical case study.

  • 岡本 峰基, 霜野 慧亮, 田川 泰敬
    2024 年 90 巻 931 号 p. 23-00276
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/28
    ジャーナル オープンアクセス

    A shaking table is a device used to examine the vibration characteristics of a specimen by applying vibration to it, and is used to evaluate the earthquake resistance of buildings and the ride comfort and safety of vehicles. Therefore, it is necessary to accurately reproduce the target vibration on the shaking table in order to investigate the accurate vibration characteristics of the specimen. For this reason, experiments with shaking tables require a controller with good tracking performance. Generally, shaking tables are controlled by feedback control, which uses displacement or acceleration as the controlled variable. However, acceleration feedback control can easily achieve good tracking performance in the high-frequency range, but performance deteriorates in the low-frequency range. On the other hand, the displacement feedback control can improve the tracking performance in low frequency. Considering these characteristics of the control system, a method using a control system that fuses acceleration feedback control system and displacement feedback control system has been proposed. This method of fusing different feedback control systems is called as Controller Fusion. However, controller fusion causes problems such as deterioration of tracking performance due to interference in the control system. In this study, we formulate the interference in the control system caused by controller fusion and use its inverse characteristics as a compensator to propose a control system that does not deteriorate the tracking performance no matter what kind of feedback controller is used. Then, experiments are conducted with the specimen mounted on a 3-DOF shaking table to verify the effectiveness of the proposed control system.

設計,機素・潤滑,情報・知能,製造,システム
  • 丘 華, 山口 哲郎
    2024 年 90 巻 931 号 p. 23-00247
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/28
    ジャーナル オープンアクセス

    From the machining center (MC) user’s point of view, this paper, as the second report of a systematic study, proposes a practical approach to estimate the trajectory error of a circular arc interpolation cutter path produced by the NC linear acceleration/deceleration (Acc/Dec) processing to interpolation segment and the feed axis servo control for a target MC. A simple and convenient motion model is established for describing the behavior of the servo axes corresponding to a circular arc segment of any length processed by the linear Acc/Dec operation. Based on the model and a linearity assumption on the dynamics of servo system, an efficient simulation method is developed to precisely calculate the cutter path trajectory and the servo axis speed from the motion parameters commanded in NC program. The verification experiments have been performed on the target MC, in which the specially designed cutter paths were inspected by a cross grid measuring device, and the measured motion trajectories were compared and discussed with the ones simulated by using the same motion parameters, from different perspectives. The examination results sufficiently demonstrate the effectiveness of the proposed model and simulation method if the adopted feed rate is within the commonly used range at the production site. Therefore, as a useful tool, the approach provides a potential application possibility, i.e. beforehand estimating the influence of the NC Acc/Dec processing and the servo control on cutter path accuracy or judging the motion conditions for the machining purpose without performing an actual machining with the target MC. Moreover, a reverse compensation principle of the cutter path motion error based on the simulation results is presented and examined through an actual example. The result has proved the possibility of practical application of the principle and suggested the direction of future effort.

  • 佐々木 伸, 北村 充, 竹澤 晃弘
    2024 年 90 巻 931 号 p. 23-00252
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/27
    ジャーナル オープンアクセス

    The purpose of this paper is to construct a methodology which can produce a lightweight panel structure while being satisfied with more than one constraint by using some simple model. In this study, we chose a problem including bending stiffness and the 1st order eigen frequency as constraints and volume minimization as objective function among basic performances which a vehicle requires. So far, we have been trying to solve the problem by using a method consisting of Fully Stressed Design (FSD) and Genetic Algorithm (GA). FSD is an optimization which evaluates only stiffness of a structure based on relationship between thickness and stress, while GA, a broad array method, can have various number of objective functions and constraints. Prior to this study, the authors found a process was effective that stresses on the elements were to be equalized in the 1st step by applying FSD that made an individual superior on static stiffness. In this study, proposed method, which includes a process of equalization on normalized stresses on eigen vibrations, are added to that of static stresses in the 1st step. In the 2nd step, GA is selected. GA conducts operations, such as select, crossing, and mutation repeatedly until this attains a final solution. As for the model, we chose a sandwich panel which is equipped with top and bottom plates and interlayer lattice stiffeners. The reason for this selection is that the sandwich panel is lightweight and superior to stiffness, dumping, and strength. As a result, the obtained model presents a lightweight structure while being satisfied with the requirements of both stiffness and eigen frequency. Moreover, the proposed method attains optimized results earlier than GA without using FSD.

  • 原田 孝, 八瀬 快人
    2024 年 90 巻 931 号 p. 23-00302
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/27
    ジャーナル オープンアクセス

    This paper proposes a method for machining a miniature Gaudi-screw and nut for a miniature differential drive mechanism with an ultra-small diameter and ultra-long lead based on a square cross-section. A miniature Gaudi-screw with a square cross-section of 2 mm on one side, a 10 mm lead (57.9 degrees slope angle), a total length of 40 mm (aspect ratio 20), and a square cross-section of right and left helix nuts are developed. First, the geometry of the proposed Gaudi-screw and the reasons why it is suitable for miniaturization are explained. Then, the configuration and kinematics of the mechanism using the Gaudi-screw as a two-input, two-output differential screw mechanism are described in preparation for the operation verification experiment. Next, the minimum radii of curvature of the Gaudi-screw and nut surfaces are derived using three-dimensional surface geometry, and the ball end mill tip diameters for cutting the miniature Gaudi-screw and nut are calculated. For the machining of long miniature Gaudi screws with small diameters, a machining method that suppresses deformation during machining due to machining reaction forces are proposed, and the results of actual machining using a 5-axis NC machine are shown. In addition, a parting and assembling method for miniature nuts are proposed, and the results of actual machining are shown. A prototype of an experimental device to motorize the miniature Gaudi differential screw mechanism was fabricated, and its operations were verified.

  • 小島 昌一
    2024 年 90 巻 931 号 p. 23-00312
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/03/07
    ジャーナル オープンアクセス

    Inside realistic multi-stage geared system the dynamic meshing tooth loads are in interference mutually between meshing pairs. This report deals with this multi-stage crosstalk theoretically by Receptance Operator Procedure (ROP) that has been developed by the author. ROP leads the original governing simultaneous linear differential equations with the time-variant meshing tooth stiffness into Fredholm type simultaneous integral equations and their solution, finally into the analytical expression of dynamic tooth force or vibration amplitude. To confirm the contribution factors in dynamic behavior two fundamental sets of the multiple stage system, namely 2 stage serial gearing and planetary gearing structures are taken up for numerical experiment on analytical ROP solution. Taking a meshing takt homogeneity into consideration, the vibration amplitudes and their interference inside the serial stage system and the parallel-serial combined branching and merging system have been investigated. The singularity in dynamic interferences caused by repeated eigen value is also discussed. In conclusion, torsional linear system-rule of the geared structure is categorized into zones according to the interference state as function of system-pattern, i.e., homogeneity of meshing period, interconnecting stiffness between meshing stages, meshing phase gap and contact ratio.

生体工学,医工学,スポーツ工学,人間工学
  • 久保田 竜平, 麓 耕二
    2024 年 90 巻 931 号 p. 23-00305
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/27
    ジャーナル オープンアクセス

    Magnetic hyperthermia (MHT) is a promising cancer treatment that kills cancer cells by heating them, However, its clinical utilization is limited owing to challenges in temperature control and measurement. We attempted to clarify the heat generation and heat transfer characteristics of MNPs by measuring the temperature field inside a sample using the laser-induced fluorescence (LIF) method, a fiber-optic thermometer, and thermocouples, and to evaluate the potential risks and effectiveness of MHT. Heating experiments were conducted by fixing a heated sample under a high-frequency AC magnetic field, and the temperature field inside the sample at the end of the experiment and the temperature time series changes during the heating experiment were measured. From the heating experiments, it was confirmed that conditions exist under which MNPs efficiently generate heat, with changes in frequency and concentration. Measurements of the sample internal temperature field confirmed that the heat generated from the magnetic agar is transferred to the bioequivalent agar phantom. The experimental results suggest the possibility of achieving complete healing by magnetic hyperthermia treatment alone and the risk of cell damage to normal cells during treatment implementation.

交通・物流
  • 本堂 貴敏, 國行 翔哉, 鈴木 貢
    2024 年 90 巻 931 号 p. 23-00231
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/27
    ジャーナル オープンアクセス

    Instrumented wheelsets are widely used in the railway industry for the purpose of measurement of the wheel-rail interaction forces, which are crucial factors in a running safety assessment. Information on lateral contact position between wheel and rail is also an important factor when discussing the wheel-rail contact conditions, such as the friction coefficient at the contact point. However, it is difficult to measure the contact position by using ordinary instrumented wheelsets since they are specialized only for the measurement of interaction forces. Therefore, the authors have proposed a signal processing procedure to extract information of contact position from bridge circuits constructed for the measurement of the lateral forces between wheel and rail by using bending and shear strains of wheel webs in a previous work. The purpose of this paper is to develop an online processing system which implements the proposed signal processing procedure. The original procedure requires long computational time and is not suitable for an online processing. As the first step to develop the processing system, this paper proposes a faster algorithm of signal processing procedure based on frequency analysis for extracting information of contact position from instrumented wheelset at first. Using the faster algorithm, a multi-rate processing system was developed to acquire the strain data at a high frequency and to execute the signal processing at a low frequency. The performance of the developed system was evaluated with a single-wheelset roller-rig test.

  • 河田 哲明
    2024 年 90 巻 931 号 p. 23-00241
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/29
    ジャーナル オープンアクセス

    As the number of elderly people increases, the demand for electric wheelchairs is increasing. Among them is a joystick-type 6-wheel electric wheelchair. It has three wheels, the central wheel of which is the driving wheel in side view. This structure allows the left and right drive wheels to rotate in the opposite direction, resulting in an extremely small turning radius compared to other types. On the other hand, it is difficult to ensure the grounding performance of the wheels, including the drive wheels, due to changes in the road surface outdoors because it has 6 wheels, so it is mainly intended for indoor use. In this paper, I studied how to improve the grounding performance of the drive wheels and other wheels by using a newly devised passive link. I devised a parallel double rocker link mechanism that connects six wheels with four sets of rocker links. I found a way to improve it. As a result, it was confirmed that the prototype vehicle using the parallel double rocker link satisfies the JIS requirements.

  • 臼田 隆之, 高橋 正樹, 天野 佑基, 山下 義隆
    2024 年 90 巻 931 号 p. 23-00245
    発行日: 2024年
    公開日: 2024/03/25
    [早期公開] 公開日: 2024/02/27
    ジャーナル オープンアクセス

    Condition monitoring technology has advanced remarkably in recent years in various areas, including railways. Since the overhead catenary system and the pantograph in railway does not have enough redundancy, failures of the overhead catenary system or the pantograph will result in long downtime in railway operations. For preventing such failures efficiently, it is effective to apply condition monitoring methods to detect the pantograph failure on the overhead catenary system. To Achieve stable current collection, although the lift characteristic of the pantograph must be maintained within an appropriate range, the monitoring method of lift of pantograph in actual use has been not established so far. Therefore, the authors developed a method to measure the lift of pantographs with sensors on the overhead catenary system. According to this method, the lift is obtained from the sum of hanger forces and vertical components of the tensile force of contact wire. However, this method has some problems to solve in terms of measurement error and easiness of implementation. Therefore, in this paper, the authors focus on the wave equation for each wire of the overhead catenary system to propose new four measurement methods of the pantograph lift. The proposed methods will solve the problems of the previous methods. The methods are verified using dynamic simulation of the overhead catenary system and the pantograph. It also reports that the proposed method is effective even when two pantographs pass continuously.

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