著者

森山 幸平 岡永 博夫

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.89, no.924, pp.23-00083, 2023 (Released:2023-08-25)

参考文献数

16

---

The surface of a golf ball is provided with innumerable dents called dimples to improve the flight distance. In this study, we manufactured 15 model balls in which the dimple occupancy and the dimple volume ratio was changed by the dimple diameter and the number of dimples, and the dimple shapes. Using these balls, we carried out lift and drag measurements of the rotating balls in wind tunnel experiments. Then, a flight trajectory simulation was performed based on the obtained experimental results. As a result, the influence of the base shape showed different results for both drag and lift coefficients for each occupancy. However, the drag coefficient decreased and the lift coefficient increased as the dimple volume ratio increased regardless of the dimple shape. In addition, the relationship between the lift-drag ratio and the dimple volume ratio showed that the lift-drag ratio decreased as the dimple volume ratio increased. The flight trajectory simulation results showed that the flying distance was greater for O=52.6% and O=63.1% with a conical base when the dimple volume ratio was small and the dimple depth is DD/d=4.55×10-3. Two spheres with a spherical base and a conical base at O=83.1%, also exhibited similar flying distances. However, the flight distance tends to increase as the dimple volume ratio decreases. The ball's trajectory was lower when the volume ratio was small, and higher trajectory was obtained when the occupancy ratio was high.

著者

竹田 憲生 亀山 達也

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.22-00095, (Released:2022-06-07)

参考文献数

14

---

A practical structural health monitoring has been proposed for evaluating the structural health of a whole mechanical asset by using digital twin with data collected during the operation of the asset. Digital twin can be utilized to predict the remaining useful life by estimating the variation of the physical quantity that dominates the life, even though any records of failure do no exist. However, a mechanical asset includes huge number of local hot spots where structural health should be evaluated, and accordingly, huge man-hours are required to integrate a monitoring system that evaluates the health at all the hot spots by using digital twin. A hierarchical structural health monitoring has been therefore developed to overcome this drawback. In the first stage of the health monitoring, the overview of the mechanical damage of the components included in a asset is evaluated according to a metric, D factor, that defines the cumulative damage of the components, and the assets having relatively large damage are extracted. The extracted assets are then evaluated in detail in the second stage; that is, structural health is checked at the local hot spots. The monitoring system that employs digital twin and the hierarchical health monitoring was applied to the health management of wind turbines. As the result of evaluating the structural health of the main components of wind turbines, about a hundred wind turbines can be prioritized according to the D factor. In this first stage, a surrogate model based on a machine learning was utilized for evaluating the overview of the damage with low computational cost; the approximation error of the D factor was less than 3 % by using the surrogate model. It can be therefore concluded that this practical structural health monitoring is useful for the decision making of fleet health management of mechanical assets.

著者

史 金星 山田 陸人

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

vol.89, no.922, pp.23-00054, 2023 (Released:2023-06-25)

参考文献数

20

---

Lure fishing is a well-known type of fishing that uses artificial lures instead of traditional live baits. Vibratory lure is a kind of lures performs greater vibration behavior than other kinds of lures. In common, more excellent vibration behavior of vibrating lure can attract carnivorous fish more efficiently. Up to now, lure design is generally based on the intuition of the designer, and there is little academic research on vibrating lure. In this study, we build the finite element model of a commercial vibration lure using a 3D scanner at first. Then, fluid–structure interaction (FSI) analysis is carried out to reproduce underwater motion of the vibration lure, where we can calculate the frequency of the flow induced vibration (FIV). Finally, in order to obtain the best FIV behavior of the vibration lure, based on the simulation results of FSI analysis, we perform structural design optimization of the vibration lure using the Box-Behnken design method, which belongs to the response surface methodology. In the structural design optimization, we set three design variables, which are the positions (x and z) of the weight placed in the lower part of the lure, and the eye position (i.e., the knot position between fishing line and lure) along the lure body. According to optimal results, the highest frequency of the FIV can reach 7.07 Hz. However, the present work is still in the early stage of the academic research on lure design, we aim to develop more optimization method for lure design that make lure fishing more interesting for both beginners and anglers.

著者

仲田 翔太 石川 亮太 佐藤 靖徳 高橋 勉

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.88, no.906, pp.21-00369, 2022 (Released:2022-02-25)

参考文献数

17

---

A prediction model of the fluid force on a cylindrical blade driven by the Necklace vortex is developed and verified by experiments when the yaw angle is given. Based on the measurement results of the velocity ratio of blade and wind velocity and the fluid force coefficient at zero yaw angle, a prediction model for the relationship between the rotation angle of the cylindrical blade and the fluid force coefficient considering the yaw angle was derived from the analysis of the two-dimensional velocity components acting on the cylindrical blade. The validity of the predictive model was demonstrated by experimental verification. From the comparison, it was found that there was a time delay in the formation and disappearance of the Necklace vortex. Based on the experimental results, the characteristics of the fluid force acting on the cylindrical blade were classified into five angular regions and based on the characteristics of the effective velocity ratio considering the yaw angle, the classification was made into 12 angular regions. Depending on the yaw angle, wind speed, and rotational speed of the blade, all of these regions may appear or only some of them may appear. Therefore, the yaw angle characteristics of the cylindrical blade wind turbine driven by the Necklace vortex are very complicated.

著者

仲田 翔太 佐藤 靖徳 高橋 勉

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.88, no.907, pp.21-00349, 2022 (Released:2022-03-25)

参考文献数

21

---

In a circular cylinder blade wind turbine driven by a longitudinal vortex, the torque characteristics of the turbine are greatly affected by the flow field at the blade tip. In general, wind turbines reduce drag by making the blade tips thinner. However, because this wind turbine uses a cylinder as a blade, it is important to control the flow field at the blade tip. From the experiments, it was found that the torque coefficient can be increased by attaching the endplate to the blade tips, and the rotational force can be obtained stably up to very low rotation speeds. The installation of fairing or endplates in circular cylinder blade wind turbines enables stable rotation at low speeds even under high loads, and also reduces drag at high speeds and increases the maximum speed. In the case of a disk-shaped endplate, the torque coefficient can be increased by up to 20 % by attaching an endplate with a diameter 2.5 to 3 times the diameter of the cylinder to the outer blade tip only. The L-type endplate has the effect of shifting the characteristics to the higher rotation side than the disk-type, and increases the torque coefficient at the same tip speed ratio. However, the lower limit of stable rotation becomes higher, and as a result, the value of the maximum torque coefficient obtained at high load decreases. If the endplate attached inside has a negative effect on the stable formation of the necklace vortex, it will inhibit the rotation at a low speed due to high load, making it difficult to obtain high torque.

著者

甲嶋 秀平 梶井 憲弘 細井 厚志 川田 宏之

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.871, pp.18-00435, 2019 (Released:2019-03-25)

参考文献数

25

---

Carbon fiber reinforced plastics (CFRPs) are widely used as components of marine structures. Thus, it is important to understand the degradation of the mechanical properties and its mechanism under seawater immersion. The object of this study is the influence of seawater immersion on the mechanical properties of plain woven CFRP laminates. Static tensile test and tensile fatigue test were carried out on the CFRP immersed different time under seawater for 300, 2500 and 5400 hours. The mechanical properties immersed for 300 hours was almost the same value compared with those of no immersion. However, the tensile strength immersed for both 2500 and 5400 hours reduced by 22.5% compared with that of no immersion. Then, from the fatigue results, in the low-cycle fatigue region, the fatigue strengths decreased as immersion time was longer, on the other hand, in the high-cycle fatigue region, the fatigue strength did not change significantly regardless of immersion time. As a result, the inclination of S-N curves became gentle as immersion time was longer. From observation of fracture surfaces by scanning electron microscopy (SEM), it was shown that the fiber/matrix interface deteriorated remarkably after seawater immersion. Moreover, the difference of damage growth behaviors due to immersed in seawater under fatigue loading was investigated using soft X-ray photography. On specimen immersed in seawater, the accumulation of damage expanded more widely due to interface degradation compared with that of no immersion. Considering these results, it was suggested that the static tensile strength depended on load transmission efficiency between fiber and matrix, on the other hand, the fatigue strength in high cycle fatigue region depended on the strength of fiber along 0° that had small influences by seawater immersion.

著者

山崎 貴史 松岡 常吉 横山 博史 中村 祐二

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.86, no.889, pp.20-00210, 2020 (Released:2020-09-25)

参考文献数

25

被引用文献数

1 1

---

The effects of the traveling sound wave generated by the speaker on diffusion flame were investigated experimentally. The sound frequency was varied from 50 to 1000 Hz using two sizes of loudspeakers, whose peak frequency showing the maximum sound pressure amplitude is nearly identical. A spirit lamp was used as the reference (diffusion) flame. Having irradiation of sound, the flame was inclined and stretched toward the traveling direction under specific range of the exposed frequencies and importantly, the effective range of the frequency was found to be quite different in two speakers used in this study. Precisely speaking, the deformed flame length reached its maximum value under the condition of 200 to 400 Hz for small speaker and 50 to 200 Hz for large speaker, respectively. In addition, the velocity distribution around the speaker was measured to reveal that the variation of flame length with respect to frequency, and it was found that the response against the applied frequency was rather close to that of flow velocity, not that of the acoustic pressure amplitude. Further investigation of flow field nearby the speaker clearly showed that the pump-like flow acceleration was induced by the periodic motion of the membrane of the speaker. From the above results obtained, it was confirmed that the effect of acoustic sound on the flame shall be come not only from pure acoustic wave feature but also from the factors depending on the hardware. Without the eliminating the latter effect, nature of acoustic-flame interaction behavior by using acoustic characters (e.g., frequency or acoustic pressure) is not readily available.

著者

高見 創

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.86, no.881, pp.19-00295, 2020 (Released:2020-01-25)

参考文献数

16

---

To shorten the stopping distance of the high-speed trains in case of emergency such as a huge earthquake, the author developed the small-size and light-weight aerodynamic braking device. The device increases an aerodynamic drag force of a train to achieve a high deceleration at the range of over 350 km/h without a friction between rail and wheel. The device is as miniaturized as possible in order to be installed flexibly on the train, whereby many devices with small-size drag panels are appropriately arranged throughout the train roof to obtain higher drag force. A pair of drag panels rotating around a horizontal axis which are connected by the gear can be actuated by the traveling wind without a large-size actuator. The full-scale prototype aerodynamic braking device is designed and manufactured. To examine its aerodynamic characteristics, one or two prototypes are tested on a wind tunnel facility at a maximum flow speed of 400 km/h (111 m/s). It was proven that the response time of motion from the folding position to the braking position took only 0.39 s, and the device could produce the aerodynamic drag of 2.3 kN per one unit at 400 km/h. Detached-eddy simulation (DES) is used to study the flow around a train roof with a large number of devices. The rate of change of the drag coefficient for devices with the staggered arrangement which aims to improve a total drag force of a train is compared against the standard parallel arrangement at U = 360 km/h. The staggered arrangement could increase the total drag coefficients 10.3 percent as compared to the standard parallel arrangement.

著者

下野 智史 児玉 斎 鈴木 克幸

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.15-00294, (Released:2016-01-22)

参考文献数

13

被引用文献数

2 1

---

Taylor-made designs are required for golf clubs, in particularly for golf shafts, because the golf equipment have great effects on the performances of players. Our objective is to establish an optimal design method of golf shafts for each player depending on their swing motions. We measured the swing motions with a 6-axis sensor that inserted into the grip end not to prevent normal motions. We analyzed the head motions at the impact using FEM with the swing data, and we tried to figure out the best shaft spec for an optimal impact. The optimization algorithm was followed 4 skilled shaft designers, which means that we had optimized the 4 SPECs in turn as below; 1) Weight, 2) Torque, 3) Flex, 4) EI pattern. As a result, the distance of a subject, a female professional golfer of JLPGA, was improved 11yrd more with the optimized shaft, and she uses the optimized shaft for more than 2 years. Thus our method was proven to be efficacious for some typical players. On the other hand, we were not able to get desired results for another 2 subjects. We believe the causes of undesired results are that some players change their swing motions depending on the shaft spec. We ought to consider the motion adjustment depending on the shaft spec in order to design optimal golf shafts for each player in the near future.

著者

朝岡 洸太 和久田 康平 金本 凌 諏訪 秀樹 荒木 拓人

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.22-00325, (Released:2023-03-02)

参考文献数

24

---

Various fields, such as the paper industry, chemical engineering, and renewable energy, are faced with gas-liquid two-phase flows and are being studied by visualization and observation. Although it is necessary to quantitatively evaluate the characteristics of bubbles, there is a limitation in the amount of labor required for detection and measurement by human observation of images. There are no examples for bubbles in polymer electrolyte membrane water electrolysis (PEMWE), where the bubbles in PEMWE have heterogeneous backgrounds, unpatterned patterns, and unclear bubble contours. Existing methods for detecting these bubbles are not expected to be accurate enough. In this study, a deep learning-based bubble detection method using convolutional neural networks (CNN) was developed for bubbles in PEMWE. Our method has two novel approaches: first, we developed an algorithm that automatically draws a pseudo-bubble image based on an actual bubble image on an arbitrary background as a method for automatically generating training data for the CNNs. Second, we developed a CNN-based bubble detection method that uses the motion of bubbles, specifically, the difference between the bubble image and the image from one frame ago, as input. Finally, we tested the algorithm on bubble images in a PEMWE and achieved an F1 score of 0.83 or better for all current densities of 0.5, 1, 2, and 3 A/cm2, and an F1 score of 0.844 for the entire detection.

著者

横田 真斗 久富 彩音 石井 裕 渡辺 富夫

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.22-00228, (Released:2023-02-22)

参考文献数

25

---

Focusing on the correlation between speech sounds and body movements, we developed a voice-driven embodied entrainment character called InterActor that automatically generates communicative motions from speech, and demonstrated the effectiveness of the system. We also developed a communication agent that responds appropriately to utterance contents by focusing on words in speech using speech recognition. However, these systems simply generate body motions from the burst-pause of speech. The response actions corresponding to speaker’s speech speeds were not considered. In this paper, we analyze the relationship between an individual’s speech activity and speech speed[mora/s] from various speech experiments with the aim of facilitating speech according to speaker’s speech characteristics. We develop a voice-driven embodied entrainment system which performs nodding with different speeds according to speech speeds based on speech recognition. Based on the results of the speech experiments, we conduct an online evaluation experiment using videos of multiple speakers with different speaking speeds using the robot as a platform to verify the effectiveness of the response actions generated by the system.

著者

天寅 喬文 渕端 学

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.18-00399, (Released:2019-06-27)

参考文献数

8

---

In recent years, NOx and soot contained in the exhaust gas of diesel engines become problems. Currently they are elutriated by exhaust gas aftertreatment devices, which make the engine system more complicated. Therefore, we focused on emulsion fuel, which is known as one of the simultaneous reduction technology of NOx and soot. Although emulsion fuels are generally characterized by its water content, some literatures report that the effect on the diesel engine performance could not be controlled by the water content properly. Therefore, we focused on dispersed water droplet diameter as the other factor. In this study, we prepared emulsion fuels of different water droplet diameters and investigated the exhaust gas and power performance of a diesel engine with these fuels. The emulsion fuels consist of light oil, water and surfactant. We added 2.0 vol% of surfactant whose HLB value was adjusted to 6.0 to light oil. The water content was 10 and 15 vol%. We prepared emulsion fuels of three different mean dispersed water droplet diameters. The test fuel was 6 types of emulsion fuel (3 kinds of dispersed water droplet diameter, water content 10 and 15 vol%) and light oil. The diesel engine used in our experiment was of air-cooled, single-cylinder, jerk pump driven direct injection type. The displacement is 320 cc. We measured in-cylinder pressure, ignition delay, exhaust gas emission (NOx, Soot and CO) and power performance (Output power and Thermal efficiency). We found a relationship between the Sauter Mean Diameter of dispersed water droplets (DS.M.D.) and each parameter. The smaller DS.M.D. is, the more the NOx and soot are reduced. On the other hand, the bigger DS.M.D. is, the higher the output and thermal efficiency are.

著者

山本 茂 東 倖成 髙木 山河 堀川 徳二郎 山崎 之博 宇治川 弘人

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

vol.88, no.915, pp.22-00097, 2022 (Released:2022-11-25)

参考文献数

12

被引用文献数

1

---

Strip walking is an unstable lateral movement in a hot strip finishing mill that causes the strip to crash into the side guides, resulting in a tail pinch where the strip is rolled in a folded state. Strip walking should be appropriately controlled to prevent tail pinches, and an adequate mathematical model is essential to design the strip steering control. In this paper, the traditional model and a recently proposed model representing strip walking are numerically compared, and the latter is shown to characterize the details of the actual phenomenon. Such a mathematical model derivation makes it possible to use model predictive control to optimally control the strip walking, considering the rate limit constraint of the actuator. However, model predictive control requires time-consuming optimization computation. Thus, control performance deteriorates with longer control periods. In this paper, we propose a new model prediction control method to reduce optimization computation time with discretized control input that enables fast discrete optimization instead of slow continuous optimization. It is also shown that fixing the misalignment between the roll and steel strip centers is insufficient to prevent the tail pinch. Moreover, it is vital to suppress the rotational motion of the steel strip by using numerical simulations.

著者

花之内 健仁 松岡 連太郎 青木 僚汰 森田 崇裕 境 慎司

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.88, no.907, pp.21-00151, 2022 (Released:2022-03-25)

参考文献数

12

---

Ultrasound transmission gel has been normally used as a material fills the gap between the transducer of the ultrasound and patient’s skin. Alternatively, however, it can be used as a trial bioink for the 3D bio-printer, which is identified as one material for checking its printability at the preliminary phase. The purpose of this study was to clarify whether the ultrasound transmission gel can be used as the trial bioink. For this purpose, we investigated the viscosity of some kinds of the ultrasound transmission gel, and compared with commercially available one. And also we measured the width of the printed lines with the ultrasound transmission gel in comparison with the perspective width. According to our results, we concluded that the ultrasound transmission gel can be used as the trial bioink as long as selecting appropriate viscosity type.

著者

森田 直樹 堀江 正信 須藤 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

vol.86, no.882, pp.19-00337, 2020 (Released:2020-02-25)

参考文献数

22

---

In numerical analyses based on unstructured meshes represented by the finite element method, quadrilateral and hexa-hedral meshes are used for a two-dimensional and a three-dimensional analyses, respectively, from the viewpoint of calculation accuracy and computation time. However, a method for automatically generating quadrilateral and hexahedral meshes has not been established thus far; in addition, a considerable amount of effort is required to perform manual mesh modifications. Mesh generation based on the frame field method is an effective technique to extract high quality quadrilateral and hexahedral meshes through the optimization of the posture of a frame with rotational symmetry. This method needs to solve a mixed-integer programming (MIP) problem while extracting the quadrilateral and hexahedral mesh using integer grid maps. When solving an MIP using a greedy method, solving a simultaneous equation is required approximately O(M) times, where M is the number of integer constraints. In this study, we propose a method to obtain a quadrilateral mesh by solving a simultaneous equation approximately O(1) times. In this method, the frame field is calculated using finite element discretization, and the finite element mesh is appropriately remeshed to be aligned with the integer grid resulting from the frame field optimization. The proposed method can reduce the amount of computation required to obtain integer grid maps for mesh extraction, without impairing the mesh quality. The proposed method is evaluated with respect to by mesh quality using the aspect ratio and the scaled Jacobian. Numerical examples demonstrate that the mesh quality is comparable to or better than that produced by conventional methods and manual procedures.

著者

益田 快理 Le Van Lich 嶋田 隆広 北村 隆行

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

vol.85, no.876, pp.19-00175, 2019 (Released:2019-08-25)

参考文献数

26

---

Ferroelectric behavior in mechanically strained SrTiO3 nanoporous is investigated using phase-field models. We find, in the paraelectric nanoporous, periodically arrayed ferroelectric nano-region is formed due to strain concentration, namely, polarization vortices emerge around each pore. Each ferroelectric region expands and connects each other with increasing strain, and ferroelectric network is finally formed. Since these ferroelectric regions can be regarded as a periodically arrayed ferroelectric nanomaterial embedded in a paraelectric material, this result means that periodically arrayed ferroelectric nanostructure, which may lead to novel functionalities, can be tailored through mechanical load. In addition, we find that the variation of load changes the geometrical characteristics of the ferroelectric structure such as shape and direction. Our finding provides a new concept to engineer future ferroelectric nanodevices by giving a new role to mechanical load.

著者

山根 清美 湯浅 皓太 伊藤 孝起 小砂 匡 竹村 幾史

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.88, no.916, pp.22-00198, 2022 (Released:2022-12-25)

参考文献数

10

---

We propose a method for solving differential equations implicitly using iterative calculations in spreadsheet software. This method uses difference equations by discretizing the coordinates of the independent variables with cells of spreadsheet for analysis. Thus, the equations are embedded in the cells performing substitution of grid point. In addition, the embedded equations are solved by Newton’s method, and the iterative function of the spreadsheet software is used in the calculation. This method can be applied even when the differential equation is discretized by an implicit solution method. Therefore, it can be applied to ordinary and partial differential equations of different types. The advantages of discretization using the implicit method (high computational accuracy, large time increments) are also presented in this paper. The analysis procedure is almost the same regardless of the type of equation. In this paper, as an example, a simple differential equation was analyzed using Microsoft Excel, a typical spreadsheet software, to illustrate the method. The results are also shown by the analysis of the gas lubrication equation.

著者

山根 清美 湯浅 皓太 伊藤 孝起 小砂 匡 竹村 幾史

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.22-00198, (Released:2022-11-28)

参考文献数

10

---

We propose a method for solving differential equations implicitly using iterative calculations in spreadsheet software. This method uses difference equations by discretizing the coordinates of the independent variables with cells of spreadsheet for analysis. Thus, the equations are embedded in the cells performing substitution of grid point. In addition, the embedded equations are solved by Newton’s method, and the iterative function of the spreadsheet software is used in the calculation. This method can be applied even when the differential equation is discretized by an implicit solution method. Therefore, it can be applied to ordinary and partial differential equations of different types. The advantages of discretization using the implicit method (high computational accuracy, large time increments) are also presented in this paper. The analysis procedure is almost the same regardless of the type of equation. In this paper, as an example, a simple differential equation was analyzed using Microsoft Excel, a typical spreadsheet software, to illustrate the method. The results are also shown by the analysis of the gas lubrication equation.

著者

福井 貴大 松川 宗一郎 福岡 泰宏

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.870, pp.18-00360, 2019 (Released:2019-02-25)

参考文献数

57

---

This study aims to suggest a method for achieving an autonomous gait transition according to speed for a four-legged robot pacing at medium speeds. Our quadruped robot is simply designed and applies a central pattern generator (CPG) for each leg. Each leg is controlled by a PD controller based on a rhythmic output from the CPG. The four CPGs are coupled, and a hard-wired CPG network is constructed to generate a default pace pattern. In addition, we apply feedback of the body tilt to the CPG as vestibular sensory feedback. As a result, our robot safely locomotes at various speeds by autonomously changing the gait from walking to pacing to rotary galloping according to speed, despite the fact that the walk and rotary gallop are not predefined. A factor that causes the gaits' emergence is considered the body oscillation that changes according to the speed. The body oscillation exhibits a double peak per leg frequency at low speeds, no peak at medium speeds, and a single peak at high speeds. The phase differences between the four legs are adjusted according to the body oscillation by feeding the body tilt back to the CPG. The gait transition is triggered only by the body tilt angle, we expect that the suggested method can be generally used for quadruped robots.

著者

西川 一男 古川 浩二 河手 功 農沢 隆秀 辻 敏夫

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.80, no.816, pp.BMS0247, 2014 (Released:2014-08-25)

参考文献数

8

被引用文献数

1

---

In the study reported here, the operational characteristics of a human-gearshift lever system were experimentally analyzed in consideration of the mechanical properties of the human arm and related effects on muscle activity. The results highlighted three points in particular: (1) It is possible to determine positioning that facilitates operation as well as the operational direction of the gearshift lever based on force manipulability in consideration of human joint-torque characteristics; (2) subjects feel that handling is easier when arm muscle activities in push and pull operations are almost equal during translational lever movement; and (3) the gearshift lever operation speed and the force-stroke characteristics have a very significant effect on whether operation is favorable or poor. Comprehensive consideration of these results is expected to be useful in the design of a human-vehicle gearshift lever system.