著者

野田 雅貴 野口 悠暉 山田 崇恭

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.896, pp.20-00412, 2021 (Released:2021-04-25)

参考文献数

35

被引用文献数

1 4

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This paper provides a vector-valued level set-based topology optimization method for multiple materials. The proposed method is characterized by a perfectly symmetric representation of multi-material by a vector valued level set function, which lowers the dependence of initial configuration in the optimization calculation. The problem that the multi-material optimal configuration depends on how the parameters are given, due to the asymmetric material representation, is fundamentally solved. Also, this paper implements the method to adjust the geometrical complexity of optimal configurations with the regularization parameter. First, a topology optimization problem is formulated based on the representation by the perfectly symmetric vector-valued level set function, and the method to regularize the optimization problem is generalized for multi-material topology optimization. Next, we construct an optimization algorithm in which the level set function is updated by the reaction-diffusion equation. Finally, two- and three-dimensional numerical examples are shown to confirm the validity and utility of the proposed topology optimization method.

著者

新谷 浩平 畔上 秀幸 山田 崇恭

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.900, pp.21-00138, 2021 (Released:2021-08-25)

参考文献数

30

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This paper proposes a solution to a multi-material robust topology optimization problem of density type considering material uncertainties based on H1 gradient method. A material interpolation with respect to the density is introduced using the rational approximation of material properties (RAMP) and generalized it for the case with an arbitrary number of materials. Material uncertainty is considered by introducing random variables in the material interpolation scheme. The probability density functions of the random variables are assumed to be given. The topology optimization is formulated using the density which is given by a sigmoid function of the design variable. A weighted sum of the mean and standard deviation of the mean compliance is used as the objective function to control the tradeoff between optimality and robustness. To evaluate statistical moments of the objective function effectively, the univariate dimension reduction (UDR) and the Gauss-type quadrature sampling are introduced. A scheme to solve the robust topology optimization problem is presented using an iterative algorithm based on the H1 gradient method for reshaping. Examples of a two-dimensional cantilever beam under various material uncertainty exhibit the efficiency and flexibility of the approach. The accuracy of UDR is validated by comparing the results to the Monte Carlo approach.

著者

永田 恵輔 沖野 友洋 高野 純一

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.903, pp.21-00117, 2021 (Released:2021-11-25)

参考文献数

14

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Although the number of accidents at level crossings in Japan has been decreasing annually, there is still possibility of such accidents to occur due to wrong-way entry. Therefore, it is essential to study the crashworthiness of rail vehicles in level-crossing accidents. Given that there are many possible collision scenarios for such accidents, it is useful to perform a comprehensive analysis of these scenarios. To investigate the crushing characteristics of a double-skinned aluminum-alloy car body structure for a conventional railway line, we conducted impact compression tests. The impact condition compresses the overall specimen's end face (overall compression condition) and part of its end face (local compression condition). The results of the impact compression tests were as follows. Buckling was the main cause of failure in the overall compression condition, whereas shear crushing was the main cause of failure in the local compression condition. Finite Element Method (FEM) analysis was also conducted in which several material rupture laws were used and compared with the test results. No appropriate solution could be obtained when the equivalent plastic strain was used as a threshold, whereas the results of analyses using the ESI-Wilkins-Kamoulakos (EWK) model showed good agreement with those of the experiments in both compression conditions.

著者

菅野 達也 壇 裕介 岡島 寛 松永 信智

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.82, no.840, pp.15-00690-15-00690, 2016 (Released:2016-08-25)

参考文献数

19

被引用文献数

4

---

In aging society, welfare personal vehicles have been widely used to improve the quality of life of elderly and handicapped persons. However, it is difficult for the users to steer the vehicle in narrow buildings. Accordingly, platoon driving of welfare personal vehicles has attracted attention as one of the effective leading methods. The platoon driving system consists of the longitudinal control and the lateral control. The longitudinal control is based on Adaptive Cruise Control. If the vehicle parameters are adjusted for each user’s driving ability, the longitudinal control will be string unstable in the worst case. As for the lateral control, the following vehicle tracks the preceding vehicle according to the target point following algorithm. The following vehicle may collide with a wall due to the large tracking error at a sharp corner in buildings. In this paper, the robust and precise platoon driving system is proposed to realize the safe platoon driving. Firstly, the longitudinal controller stably keeps the inter-vehicle distance regardless of the short time-headway. Secondary, the lateral controller precisely tracks the wheel track of preceding vehicle by using way-points. Thirdly, the robust platoon control for the different vehicle dynamics is designed by Model Error Compensator. Finally, the effectiveness of our proposed system is evaluated by the driving experiments.

著者

沖野 友洋 永田 恵輔 高野 純一 小林 秀敏

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.902, pp.21-00073, 2021 (Released:2021-10-25)

参考文献数

19

---

The crash safety structure of the railway vehicles is important as one of the safety measures against the train crews and the passengers in the event of a collision accident. It is impractical to perform collision testing many times using the actual train unit to design the crash safety structure, whereby the numerical simulation is effective and it is important to validate the analytical accuracy. However, there are few studies of collision tests and numerical simulations using actual size carbody structures according to Japanese design standards, and even fundamental data have not been sufficiently obtained. Therefore, firstly, the authors performed the collision test of an actual-size partial stainless-steel carbody structure of a railway leading vehicle against a rigid wall and finite element analysis under the same condition as the test for the purpose of validating and improving the analytical accuracy of numerical simulation. Secondly, we carried out the collision test of the same carbody structure of a railway leading vehicle against a typical large dump truck in Japan and obtained the fundamental data such as the time histories of the impact compression load and the acceleration of the carbody structure as well as the deformational and fractural behavior of them. We also performed FE analysis under the same condition as the experimental test and compared the numerical result to the experimental one. As a result, the numerical result was consistent with the experimental result. Finally, we expanded the partial carbody structure model to a single carbody model and carried out the collision analysis of it against a large dump truck. Thereby, the impact deformation and fracture behavior of the railway carbody under the actual level-crossing accident were estimated.

著者

蔭山 雅洋 田中 成典 山本 雄平 鳴尾 丈司

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.902, pp.21-00158, 2021 (Released:2021-10-25)

参考文献数

33

---

In recent years, as measurement devices have advanced due to sensor and information technology, we have been able to measure bat swing data just after baseball impact. Therefore, the purpose of this study was to examine the characteristics of a batter’s swing using batting skill assessments from baseball coaches with significant experience. Finally, the practicality and effectiveness of baseball coaching methods, particularly for batting, were verified through this study. The subjects were 25 male university baseball players (age: 19.8 ± 1.0 yrs, body height: 174.5 ± 5.4 cm; body weight: 72.8 ± 5.1 kg). The participants were instructed to hit the ball placed on a tee stand. Nine types of tee-batting positions (course / height) were set for each participant depending on the upper and lower limits of the strike zone according to the baseball rules. Our main findings were as follows: 1) The swing characteristics (Depth: swing time and vertical bat angle, Height: head speed, rolling angular velocity, bat radius of rotation, horizontal bat angle, and vertical bat angle, Course: rolling angular velocity) varied with respect to ball positions, 2) Through batting skill assessment by two baseball coaches with significant experience, a good batter’s swing can be characterized as high bat speed, short swing time, and high efficiency of rotational movement around the vertical axis. Additionally, the coaches suggested that for a good batter’s swing, the vertical bat angle should be stable and smaller than 9°. These results provide useful information on assessment of bat swing training methods and exercises to hit the ball to different positions. Furthermore, this study can aid baseball coaches and/or players to objectively analyze a bat swing of a player.

著者

徳永 健志 門脇 弘子 森 浩二 齊藤 俊

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.898, pp.20-00319, 2021 (Released:2021-06-25)

参考文献数

10

---

The prevention of an arteriosclerosis, which is a major cause of death in the world has social significance. In previous studies, blood vessel elasticity was estimated by using parameters of blood vessel model. However, the effect of wave propagation on the estimation was ignored. It is not clear how these features affect the estimation of blood vessel elasticity in clinic. In this study, the coupled model of blood vessel and blood flow based on the coupled wave theory was proposed on the assumption that the viscosity is more strongly influenced by blood flow than by blood vessels. Identifying the model parameters of elastic pipes subjected to cyclic pressure fluctuations by using measured pressure and displacement data, we concluded that the coupled model may be applicable for estimating the vessel stiffness in clinical practice.

著者

五味 健二 新津 靖

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.82, no.838, pp.15-00498, 2016 (Released:2016-06-25)

参考文献数

37

---

Understanding stress or strain distribution or birefringence properties is important for proper industrial application of polymer films. For example, it is very important to control the stress and birefringence distribution in polymer films that are used for liquid crystal displays of PCs or smart phones, etc. for their performance improvement. As another example, it is very important to understand the stress distribution in packaging polymer films for reliability management of the package because the forming accuracy depends on the stress distribution in the films. Photoelastic analysis is suitable to understand stress, strain distribution and birefringence properties on polymer films; however, understanding of the stress-optical or strain-optical coefficients of the polymer is indispensable when using the analyzing method. In this study, the influence of displacement rate, stress orientation and stress history on birefringence properties is measured for polyvinylidene chloride (PVDC) at room temperature as an example of semi-crystalline polymer films. The stress-optical coefficient of PVDC depends on the displacement rate, stress orientation and stress history. On the other hand, the strain-optical coefficient of PVDC is approximately independent of them. These phenomena are explained by the result from the viscosity, polymer chain orientation and strain-induced crystallization in PVDC. There is potential given that strain-optical coefficients for semi-crystalline rubbery polymers are approximately independent of the displacement rate, stress orientation and stress history on some conditions because of the mechanism of the phenomenon.

著者

冨田 将嗣 下山 幸治 江原 由希子 山田 想 國領 喬

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集

巻号頁・発行日

vol.84, no.859, pp.17-00390-17-00390, 2018

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<p>Due to energy shortage and environmental protection, reduction of energy consumption and CO₂ emissions has been demanded. A smart home system is now expected as one of the solutions to satisfy these demands by using various home-energy devices such as cogeneration system, electric vehicle, and stationary battery in cooperation with each other. This paper analyzes the time-series dataset of the optimized home-energy device control, which minimize energy cost including initial investment and CO₂ emission on a sunny winter day, by the proper orthogonal decomposition (POD). POD extracts specific rules that discharging a stationary battery in the daytime with higher power unit price and operating a cogeneration system in the time when electricity and heat demands exist are significant for energy cost reduction. Thus, POD helps to consider universal rules which will be effective anytime for home energy management.</p>

著者

新部 純三 熊谷 正芳 田邉 晃弘 水野 湧太

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.21-00082, (Released:2021-08-05)

参考文献数

13

被引用文献数

2

---

Although elastic limit and tensile strength are essential for mechanical strength design, the measurement of high hardness materials is a challenge due to their sensitivity on notches. As an alternative, the tensile strength can be easily assumed from hardness using the conversion table (e.g. SAE J 417); however, the table does not include the data for high hardness region, namely tempered materials at low temperature. We performed tensile tests and obtained elastic limits and tensile strengths of quenched martensitic medium-carbon steel with tempering at several temperatures. The hardness was monotonically decreased with the increase of tempering temperature. However, the tensile strength and elastic limit improved as the increase of temperature at low tempering temperature. In contrast, at high tempering temperature, the tensile strength and elastic limit were decreased with increase of tempering temperature. Consequently, the ratios of hardness to tensile strength or elastic limit were changed below or above the transition point. The ratios were constant below a tempering temperature (290 ℃ for elastic limit and 200 ℃-300 ℃ for tensile strength in the present experiments) and increased with the increase of the tempering temperature above the temperature. The variation of the ratio, hardness to tensile strength, is due to the brittle fracture on high hardness specimens before reaching the threshold to start plastic instability. In addition to, it is considered that the variation of the ratio, hardness to elastic limit, is caused by another mechanism, a decrease in elastic limit due to mobile dislocations.

著者

牧野 裕介 高野 靖

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.899, pp.21-00052, 2021 (Released:2021-07-25)

参考文献数

19

---

The variation of the noise metrics of a group of sound sources due to its movement at a constant velocity along a straight track is discussed in the paper. When sound sources move, frequency and amplitude modulation is observed in the radiated sound field. The frequency and amplitude increase when sound sources are approaching and decrease when going away. We found that when frequency and amplitude modulation were considered, the calculated noise levels LAmax, LASmax, LAeq,T became larger than the calculated levels without their consideration. The difference of the calculated levels between the cases increased with respect to the sound source velocity. This difference was independent of distance between the track and the receiving point. Approximating discrete sound sources in line by a finite line source would underestimate the noise level. The level of this underestimation would increase by decreasing source division. The underestimated level was calculated for sources with reference noise spectrum for rolling stocks with a constant sound power level as we focused on the influence of frequency and amplitude modulation on the radiated sound field. The underestimated level was large for LAmax and LASmax compared with LAeq,T. The difference of the calculated levels between the cases decreased monotonically with respect to the source frequency.

著者

西田 麻希子 渡辺 富夫 石井 裕

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.85, no.880, pp.19-00159, 2019 (Released:2019-12-25)

参考文献数

26

被引用文献数

3 1

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We have already developed a speech-driven embodied entrainment CG character system called “InterActor” which generates communicative motions and actions such as nods for entrained interaction from speech rhythm based on only voice input. Conventional InterActor performed the entrained communicative body movements and actions based on speech input without a voice back-channel. In this study, we develop an embodied character system with the voice backchannel based on the embodied interaction model. Two experiments are performed to confirm the effectiveness of the system by sensory evaluation. In the first experiment, the effects of the automatic generation and presentation method of the voice back-channel are examined in each situation with and without character presentation. In the second experiment, the frequency of the voice back-channel to nodding motion is examined. The effectiveness of the system is confirmed from these experimental results.

著者

山本 大輔

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.898, pp.21-00011, 2021 (Released:2021-06-25)

参考文献数

10

被引用文献数

2

---

It is generally known that the groove on tire tread can increase the friction force between the tire and the road surface under wet condition because of the improvement of drainage performance. Although wheel tread of actual railway rolling stocks have a wheel turning trace like the groove on tire tread, the characteristics of tangential contact force of the wheel/rail under wet condition is not clarified in detail. In this study, the tangential contact force measurement using a pair of small cylindrical specimens was carried out to investigate the relationship between the wheel turning trace and the friction force under wet condition. The experimental result shows the friction force under wet condition does not increase due to high iron’s stiffness if the wheel turning trace provided on the tread. On the other hand, it is also confirmed that the wheel turning trace has a reduction effect of the variation of the friction coefficient under wet condition. From the numerical analysis based on these experimental results, it is clarified that the longitudinal vibration of the vehicle can be decreased if the wheel has the wheel turning trace in case of the braking running under semi-wet condition.

著者

白石 聖稀 李 根浩 豊田 彬敏 米倉 裕貴 野口 尚人

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.16-00471, (Released:2017-04-14)

参考文献数

10

---

This paper addresses the mechanical issue of a novel wheel design capable of step climbing toward more convenient utilization of assist vehicles such as wheelchairs and walkers. Despite the promotion of barrier-free environments, uneven floors with dips and depressions, thresholds, and steps have still been encountered in our daily routines. To overcome these difficulties, a step-climbing mechanism and its device are developed, allowing wheeled robots to ascend a step where its height is higher than the radius of the wheel. By applying the proposed step-climbing device into the robot, it enables potential users to minimize a physical burden during step climbing. This helps the users live independently and maintain their daily routines, not requiring caregivers and/or medical staff. What is the most important aspect from the practical point of view is how to realize the mechanism without additional wheels and linear guides. This paper describes the mechanical design by controlling axial translation in detail. By using a robotic wheelchair equipped with the proposed device, extensive evaluations are tested and analyzed.

著者

桧山 莉央 長岡 大志 坪井 一洋 野田 茂穂 姫野 龍太郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.21-00050, (Released:2021-06-18)

参考文献数

15

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We develop an output simulator for a baseball-type acceleration sensor in which one three-axis sensor for low acceleration and three sensors for high acceleration are installed. The acceleration vector at any position inside this ball-type sensor in rotational motion is formulated on the basis of the assumption that all the sensors are in rigid configuration. Since this simulator can estimate kinematically the acceleration under the change in time of rotation axis on the sensor coordinate system, we investigate the behavior of the rotation axis suggested in the previous flight experiment. In order to confirm the accuracy of the sensor outputs, preliminary experiment is performed, in which acceleration outputs are measured by rolling the ball-type sensor along a slope. The comparison of obtained acceleration outputs with theoretical values shows sufficient agreement. At the same time, the moment of inertia of the ball-type sensor is measured. Sensor outputs are simulated under two different conditions, in one of which the rotation axis is changing in time and the axis is fixed in the other. As the result, the acceleration output in the former condition varies linearly while the output keeps almost constant in the latter. The measured outputs of the flight experiment successfully reappear in the results under the former condition. The error between the simulated and measured outputs is calculated to 18 trial data of straight and curve balls, and the errors in the former condition become smaller than those in the latter. The present result therefore concludes that the rotation axis of the ball-type sensor in flight changes with time.

著者

亀谷 均 内村 和弘 樋野 貴規 山根 勁

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.16-00493, (Released:2017-02-21)

参考文献数

8

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In general, manual sorting carries out for the quality inspection of corbicula shells prior to shipment. The inspection worker drops each corbicula shells on the concrete floor, and a shell is assessed as good or bad by the sound of collision with floor. The corbicula shell containing mud or nothing is specified as a bad corbicula. This manual sorting process is time consuming and laborious. In addition, this process is often prone to mistakes. In order to overcome the problem of manual sorting, an inspection probe has been developed. The inspection probe assesses a corbicula shell as good or bad by detecting the transmitted light spectra, and it has been tested that the probe can detect good and bad corbicula shells with an accuracy of 100%. Thereafter, a quality sorting device with the inspection probe has been developed for the commercial use. A laboratory based experiments have been conducted first to evaluate the performance of developed quality sorting device. The test results showed that the sorting device can sort shells with an accuracy of about 99%. Subsequently, a comprehensive evaluation experiment have also been carried out, and the experimental results showed that our developed sorting device is able to sort corbicula shells with an accuracy of 98.6%. This results implies that the present quality sorting device is ready to use for commercial sorting of corbicula shells

著者

山長 雄亮 渡辺 信行

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.18-00109, (Released:2018-06-22)

参考文献数

5

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Hunting oscillation is unfavorable to the running stability because it can generate relatively large lateral force between the wheels and tracks. In addition, once hunting oscillation occurs, it lasts until the running speed is reduced to some degree. Therefore, we have studied global stability against hunting oscillation by conducting hunting motion tests using a real bogie on roller rigs. In this study, we confirmed that there exists a clear point where initial lateral displacement of the wheelset caused hunting oscillation. Then, we concluded that the point in question originated from unstable limit cycles, generated by subcritical Hopf bifurcation. On the basis of the obtained global stability, we devised a simple method that could make the hunting oscillation converge to the equilibrium point by oscillating the roller rig, without slowing down the rotational speed of roller rigs.

著者

山内 克哉 中川 智皓 新谷 篤彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.87, no.893, pp.20-00329, 2021 (Released:2021-01-25)

参考文献数

24

---

The car is a main means of transportation all over the world. However, many people drive a car when they travel a short distance alone, that is inefficient in cost and space. Then, personal mobility vehicle (PMV), which is one or two-seater and has high environmental performance, is recently gathering attention. We focus on the three-wheeled vehicle with leaning mechanism called Narrow Tilting Vehicle (NTV) or narrow tilting three-wheeled (NTTW). Leaning mechanism, which gives tires degree of freedom, has an effect of stable cornering in the case of short tread width vehicle. To compere the motion of each leaning mechanism, we model the two types of NTV. One has two front frame which are linked to vehicle body by the arm and rotating respectively around the joint. The other one has a front frame that has two tires connected by the link. We derived equation of motion by referring to Sharp’s 4 DOF two-wheeled vehicle model, and carried out the three kinds of numerical analysis, eigenvalue analysis, modal analysis and running simulation. Through eigenvalue and modal analysis, we find out that NTVs have the same modes as Sharp’s 4 DOF model does, and they have the characteristic mode which vibrates steering and leaning mechanism. By running simulation, NTVs required larger steering torque than two-wheeled vehicle when the vehicle turn at the same angle.

著者

八瀬 快人 佐々木 大輔 門脇 惇 安原 拓海

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.20-00173, (Released:2021-05-14)

参考文献数

20

被引用文献数

2

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Kyphosis causes decline in respiratory and circulatory functions owing to compresses of internal organs. The purpose of this study is to develop a posture keep assist device. The device is constructed with multiple resin components and McKibben type artificial rubber muscle. This device at initial state has a flexibility because the resin components are separated. On the other hand, the resin component can be connected by pressurized artificial muscle. The shape of device in which all resin components are connected imitates spine-curve to fit human back. So, the proposed device can retain entire range of trunk. Target pressure to correct posture is determined from the mathematical model of artificial muscle. In this paper, the structure of device is described, and control method to retain posture based on artificial muscle model is discussed. Finally, effectiveness of the device is verified from experiments in which subject wears this device actually. We reveal correcting trunk posture by using the device from the results.

著者

大畠 英一郎 押領司 一浩

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集

巻号頁・発行日

2021

---

<p>Several high energy ignitions have been proposed to improve ignition performance of diluted combustion recently. One of the major issues in the high energy ignition systems is heat generation of an ignition coil due to increase of power consumption. This study proposes a method to reduce electricity consumption by controlling time distribution of discharge energy while keeping the ignition performance. The following conclusions were obtained as results of verification with an actual engine. (1) A concept for reducing the power supply-demand difference that does not inhibit flame core growth was proposed. (2) To reduce the power supply-demand difference, an ignition coil with an additional active coil was fabricated to enable time distribution control of ignition energy. (3) By controlling the time distribution of ignition energy, both energy saving and ignitability of ignition were achieved, and the prospect of net fuel consumption improvement was obtained.</p>