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Dr. Takehito Kikuchi
Department of Mechatronics, Faculty of Engineering, Oita University, Oita, Japan

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0 Mechatronics
0 Rehabilitation robotics
0 Virtual reality and application of functioncal fluids. He developed or researched ER (electro-rheological) fluid actuators and brakes
0 MR (magneto-rheological) fluid actuators and brakes
0 A training machine using ER/

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Virtual reality and application of functioncal fluids. He developed or researched ER (electro-rheological) fluid actuators and brakes

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Research article
Published: 25 July 2020 in Journal of Intelligent Material Systems and Structures
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Magnetorheological fluids are composite materials made of ferromagnetic particles, medium oils, and several types of additives. We have developed actuation systems for the fine haptic control of master–slave robots. In this study, we proposed a new structure of a magnetorheological fluid–based actuator suitable for haptic devices. For the basic structure of the actuator, we proposed a twin-driven magnetorheological fluid actuator using two multi-layered disc-type magnetorheological fluid clutches for haptics. We conducted performance measures for the magnetorheological fluid clutches for haptics with three commercially available magnetorheological fluids (i.e. 122EG, 132DG, and 140CG from Lord Corp.). The experimental results show that 132DG is a better material for force control. Then, we proposed two types of twin-driven magnetorheological fluid actuators (i.e. link type and belt type) and compared their performance. The results show that the averages of the time constant are 19.1 and 16.1 ms for the link type and belt type, respectively. Furthermore, the averages of torque error are 0.033 and 0.068 N m for the link type and belt type, respectively. However, the belt-type twin-driven magnetorheological fluid actuator is better if a large range of motion is required, while the link-type twin-driven magnetorheological fluid actuator is better if accurate torque control is required.

ACS Style

Takehito Kikuchi; Isao Abe; Tomoya Nagata; Akinori Yamaguchi; Tetsumasa Takano. Twin-driven actuator with multi-layered disc magnetorheological fluid clutches for haptics. Journal of Intelligent Material Systems and Structures 2020, 32, 1313 -1322.

AMA Style

Takehito Kikuchi, Isao Abe, Tomoya Nagata, Akinori Yamaguchi, Tetsumasa Takano. Twin-driven actuator with multi-layered disc magnetorheological fluid clutches for haptics. Journal of Intelligent Material Systems and Structures. 2020; 32 (12):1313-1322.

Chicago/Turabian Style

Takehito Kikuchi; Isao Abe; Tomoya Nagata; Akinori Yamaguchi; Tetsumasa Takano. 2020. "Twin-driven actuator with multi-layered disc magnetorheological fluid clutches for haptics." Journal of Intelligent Material Systems and Structures 32, no. 12: 1313-1322.

Accepted manuscript
Published: 17 October 2019 in Engineering Research Express
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Magnetorheological fluids (MRFs) are composite materials made of ferromagnetic particles, medium oils, and several types of additives. Their rheological properties change rapidly, stably, and repeatedly when magnetic fields are applied. In this study, we developed a new torque controllable device using the MRF. An umbrella-shaped rotor with multi-layered disc structure was utilized to reduce its inertia. MRF-140CG was used as a sample material for the MRF in this study and modeled with Bingham fluid model in off-state and on-state. Design procedures and validation experiments were conducted for a prototype. According to the design results, the torque/inertia ratio was around 40000 Nm/kgm2, which is the same as a coreless motor for haptic devices. According to the experimental results, the max/min torque ratio was around 75 at 0.5 rad/s. The torque is sensitive to the rotational speed.

ACS Style

Takehito Kikuchi; Isao Abe. Low inertia torque controllable device using magnetorheological fluid & umbrella-shaped rotor. Engineering Research Express 2019, 1, 025022 .

AMA Style

Takehito Kikuchi, Isao Abe. Low inertia torque controllable device using magnetorheological fluid & umbrella-shaped rotor. Engineering Research Express. 2019; 1 (2):025022.

Chicago/Turabian Style

Takehito Kikuchi; Isao Abe. 2019. "Low inertia torque controllable device using magnetorheological fluid & umbrella-shaped rotor." Engineering Research Express 1, no. 2: 025022.

Journal article
Published: 27 February 2019 in Technologies
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The mechanical ability and usefulness of simulation systems can be improved by combining a tactile display with a remote control or medical simulation systems. In this study, a scissors-type haptic device containing magnetorheological fluid (MR fluid) in its fulcrum is developed. We evaluate the mechanical response to the applied voltage and realize the presence of mechanical stimuli when a subject grasps or cuts the corresponding objects. When the magnetic field around the MR fluid is controlled by an electric voltage of 150–500 mV, the torque linearly increases from 0.007 ± 0.000 to 0.016 ± 0.000 N m. The device can provide tactile stimuli with 0.1 s of resolution. We also determined the voltage profiles based on typical force profiles obtained during grasping/cutting processes and evaluated the torque using a mechanical evaluation system. Features of the force profiles related to the soft and sticky feels were reconstructed well.

ACS Style

Mioto Waga; Yuuki Aita; Junichi Noma; Takehito Kikuchi; Yoshimune Nonomura. Scissors-Type Haptic Device Using Magnetorheological Fluid Containing Iron Nanoparticles. Technologies 2019, 7, 26 .

AMA Style

Mioto Waga, Yuuki Aita, Junichi Noma, Takehito Kikuchi, Yoshimune Nonomura. Scissors-Type Haptic Device Using Magnetorheological Fluid Containing Iron Nanoparticles. Technologies. 2019; 7 (1):26.

Chicago/Turabian Style

Mioto Waga; Yuuki Aita; Junichi Noma; Takehito Kikuchi; Yoshimune Nonomura. 2019. "Scissors-Type Haptic Device Using Magnetorheological Fluid Containing Iron Nanoparticles." Technologies 7, no. 1: 26.

Communication
Published: 06 October 2018 in International Journal of Molecular Sciences
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Magnetorheological elastomers (MREs) are stimulus-responsive soft materials that consist of polymeric matrices and magnetic particles. In this study, large-strain response of MREs with 5 vol % of carbonyl iron (CI) particles is experimentally characterized for two different conditions: (1) shear deformation in a uniform magnetic field; and (2), compression in a heterogeneous uniaxial magnetic field. For condition (1), dynamic viscoelastic measurements were performed using a rheometer with a rotor disc and an electric magnet that generated a uniform magnetic field on disc-like material samples. For condition (2), on the other hand, three permanent magnets with different surface flux densities were used to generate a heterogeneous uniaxial magnetic field under cylindrical material samples. The experimental results were mathematically modeled, and the relationship between them was investigated. We also used finite-element method (FEM) software to estimate the uniaxial distributions of the magnetic field in the analyzed MREs for condition (2), and developed mathematical models to describe these phenomena. By using these practicable techniques, we established a simple macroscale model of the elastic properties of MREs under simple compression. We estimated the elastic properties of MREs in the small-strain regime (neo–Hookean model) and in the large-strain regime (Mooney–Rivlin model). The small-strain model explains the experimental results for strains under 5%. On the other hand, the large-strain model explains the experimental results for strains above 10%.

ACS Style

Takehito Kikuchi; Yusuke Kobayashi; Mika Kawai; Tetsu Mitsumata. Elastic Properties of Magnetorheological Elastomers in a Heterogeneous Uniaxial Magnetic Field. International Journal of Molecular Sciences 2018, 19, 3045 .

AMA Style

Takehito Kikuchi, Yusuke Kobayashi, Mika Kawai, Tetsu Mitsumata. Elastic Properties of Magnetorheological Elastomers in a Heterogeneous Uniaxial Magnetic Field. International Journal of Molecular Sciences. 2018; 19 (10):3045.

Chicago/Turabian Style

Takehito Kikuchi; Yusuke Kobayashi; Mika Kawai; Tetsu Mitsumata. 2018. "Elastic Properties of Magnetorheological Elastomers in a Heterogeneous Uniaxial Magnetic Field." International Journal of Molecular Sciences 19, no. 10: 3045.

Communication
Published: 22 January 2018 in Polymers
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The effect of a weak magnetic field on vibration transmissibility was investigated for magnetic elastomers with various volume fractions of magnetic particles. Polyurethane elastomers without magnetic particles exhibited a natural frequency at 53 Hz and were insensitive to a magnetic field of 60 mT. The natural frequency for magnetic elastomers with a volume fraction of 0.23 was 115 Hz at 0 mT, and increased to 134 Hz at 60 mT. The vibration transmissibility was independent of the magnetic field. A linear relation between the natural frequency and (G/m)1/2 was observed (G: storage modulus, m: mass), indicating that the observed vibration is basically described by a simple harmonic oscillation.

ACS Style

Hiroyuki Endo; Shunsuke Kato; Mayuko Watanebe; Takehito Kikuchi; Mika Kawai; Tetsu Mitsumata. Magnetically Tunable Vibration Transmissibility for Polyurethane Magnetic Elastomers. Polymers 2018, 10, 104 .

AMA Style

Hiroyuki Endo, Shunsuke Kato, Mayuko Watanebe, Takehito Kikuchi, Mika Kawai, Tetsu Mitsumata. Magnetically Tunable Vibration Transmissibility for Polyurethane Magnetic Elastomers. Polymers. 2018; 10 (1):104.

Chicago/Turabian Style

Hiroyuki Endo; Shunsuke Kato; Mayuko Watanebe; Takehito Kikuchi; Mika Kawai; Tetsu Mitsumata. 2018. "Magnetically Tunable Vibration Transmissibility for Polyurethane Magnetic Elastomers." Polymers 10, no. 1: 104.

Conference paper
Published: 01 January 2018 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Regardless of the importance of well-organized motions for the wrist and fingers, their effective training / assessment methods have not been developed because of their anatomical relationships. The rehabilitation robot for hand, “ReRoH,” was developed. The ReRoH installs an electric stimulation (ES) to stimulate paralyzed muscle of a wrist and fingers. In this study, we experimentally investigated optimal muscle for the ES and effect of its voltage. According to the results, common digital extensor muscle is the best muscle for its purpose, but it is also cleared that the independent stimulation for a wrist or fingers may be impossible. It is important to use the ES and a force stimulation by ER brake for ReRoH.

ACS Style

Hayato Mukai; Tomoya Nagata; Isao Abe; Takehito Kikuchi. Investigation of Position for Electric Stimulation and Development of Training Program of Rehabilitation Robot for Hand, ReRoH. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, 2018, 2P1 -G01.

AMA Style

Hayato Mukai, Tomoya Nagata, Isao Abe, Takehito Kikuchi. Investigation of Position for Electric Stimulation and Development of Training Program of Rehabilitation Robot for Hand, ReRoH. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2018; 2018 ():2P1-G01.

Chicago/Turabian Style

Hayato Mukai; Tomoya Nagata; Isao Abe; Takehito Kikuchi. 2018. "Investigation of Position for Electric Stimulation and Development of Training Program of Rehabilitation Robot for Hand, ReRoH." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, no. : 2P1-G01.

Conference paper
Published: 01 January 2018 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Movement of the knee joint of a human includes rolling and sliding. To assist the standing movement of a human, we introduced a bio-inspired knee joint (BKJ) and torque adjustment mechanism in a power assist suit on knee joint. In this study, we improved the BKJ by installing a roller on its knee to prevent excessive friction of the surface of an artificial muscle. We also proposed a shear-force sensing sheet (SSS) to evaluate unnecessary friction between human and machine in shear direction. In order to explore the optimal shapes and materials for the SSS, we fabricated a testing apparatus.

ACS Style

Tomoaki Inoue; Taiki Oshimoto; Isao Abe; Takehito Kikuchi. Development of Low-cost Shear-force Sensitive Sheet. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, 2018, 2P1 -G02.

AMA Style

Tomoaki Inoue, Taiki Oshimoto, Isao Abe, Takehito Kikuchi. Development of Low-cost Shear-force Sensitive Sheet. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2018; 2018 ():2P1-G02.

Chicago/Turabian Style

Tomoaki Inoue; Taiki Oshimoto; Isao Abe; Takehito Kikuchi. 2018. "Development of Low-cost Shear-force Sensitive Sheet." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, no. : 2P1-G02.

Conference paper
Published: 01 January 2018 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Pedal wheelchairs are useful for lower limb rehabilitation of hemiplegic patients. However, burden on non-paralyzed leg is not negligible. To prevent such fatigue on the non-paralyzed leg, power-assisted pedal wheelchair is one of the solutions. However, an optimal method for such pedaling assist has not been cleared yet. In order to provide a platform to try such power-assisted wheelchair in virtual reality (VR) environment, we have developed a VR Cycling Training and Assessment System (VR-CTAS). Two types of the power-assist method were proposed in this study; constant assist-ratio method (method 1), and opposite phase replay of healthy side torque (method 2). We measured the pedaling characteristics of three healthy subject and modeled them. These pedaling torque models were used to simulate the effect of the assist methods with a single DOF dynamic model of the wheelchair.

ACS Style

Takehito Kikuchi; Yusuke Fujii; Isao Abe. Measurement and Modeling of Pedaling Toque Characteristics for Assist Method of VR Peal Wheelchair. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, 2018, 2P2 -G02.

AMA Style

Takehito Kikuchi, Yusuke Fujii, Isao Abe. Measurement and Modeling of Pedaling Toque Characteristics for Assist Method of VR Peal Wheelchair. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2018; 2018 ():2P2-G02.

Chicago/Turabian Style

Takehito Kikuchi; Yusuke Fujii; Isao Abe. 2018. "Measurement and Modeling of Pedaling Toque Characteristics for Assist Method of VR Peal Wheelchair." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, no. : 2P2-G02.

Conference paper
Published: 01 January 2018 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Magnetorheological (MR) fluids are functional fluids whose viscosity changes when magnetic fields are applied. In this study, we focus on the optimal design of disk-type MR fluid devices. To achieve this goal, we introduced the genetic algorithm (GA) for the mechanical and electromagnetic model of the MR device. The objective function of the design was maximization of the torque ratio. Accordingly, a set of design parameters were acquired from the result of GA. To confirm the performance of the device, we conducted an analysis with the finite element method, fabricated a prototype of the device, and evaluated by using a test machine. The experimental results show that the prototype performed a maximum torque over the estimation. However, the torque ratio is not sufficient the estimation.

ACS Style

Isao Abe; Takehito Kikuchi; Kazuhiko Nishimura. Optimization Design of multi-layered disk-type MRF device. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, 2018, 2P1 -J07.

AMA Style

Isao Abe, Takehito Kikuchi, Kazuhiko Nishimura. Optimization Design of multi-layered disk-type MRF device. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2018; 2018 ():2P1-J07.

Chicago/Turabian Style

Isao Abe; Takehito Kikuchi; Kazuhiko Nishimura. 2018. "Optimization Design of multi-layered disk-type MRF device." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, no. : 2P1-J07.

Conference paper
Published: 01 January 2018 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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ACS Style

Taiki Oshimoto; Isao Abe; Takehito Kikuchi; Naoki Chijiwa; Tomohisa Yabuta; Kenichiro Tanaka; Yasue Asaumi. Suggestion of Burden-Reducing Shoes with Elastomer-Embedded Flexible Joint. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, 2018, 2A2 -G01.

AMA Style

Taiki Oshimoto, Isao Abe, Takehito Kikuchi, Naoki Chijiwa, Tomohisa Yabuta, Kenichiro Tanaka, Yasue Asaumi. Suggestion of Burden-Reducing Shoes with Elastomer-Embedded Flexible Joint. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2018; 2018 ():2A2-G01.

Chicago/Turabian Style

Taiki Oshimoto; Isao Abe; Takehito Kikuchi; Naoki Chijiwa; Tomohisa Yabuta; Kenichiro Tanaka; Yasue Asaumi. 2018. "Suggestion of Burden-Reducing Shoes with Elastomer-Embedded Flexible Joint." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2018, no. : 2A2-G01.

Conference paper
Published: 01 January 2017 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Rehabilitative trainings for hemiplegic patients by using cycling-type wheelchairs have recently concerned as one of effective ways to recover locomotion abilities. However, the mechanism and effective ways for such training with the cycling-type wheelchairs have not been cleared yet. In this study, we developed the Virtual Reality Cycling Training and Assessment System (VR-CTAS) to investigate the effect of cycling motions in rehabilitative training. We newly developed a wireless pedal torque sensor and installed it on the VR-CTAS. The measurements of the pedaling motions with the VR-CTAS were conducted.

ACS Style

Yusuke Fujii; Keisuke Mori; Isao Abe; Takehito Kikuchi. Development of Virtual Reality Cycling Training and Assessment System to investigate the effect of cycling motions in rehabilitative training. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2017, 2017, 2A1 -I01.

AMA Style

Yusuke Fujii, Keisuke Mori, Isao Abe, Takehito Kikuchi. Development of Virtual Reality Cycling Training and Assessment System to investigate the effect of cycling motions in rehabilitative training. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2017; 2017 ():2A1-I01.

Chicago/Turabian Style

Yusuke Fujii; Keisuke Mori; Isao Abe; Takehito Kikuchi. 2017. "Development of Virtual Reality Cycling Training and Assessment System to investigate the effect of cycling motions in rehabilitative training." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2017, no. : 2A1-I01.

Conference paper
Published: 01 January 2017 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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Rehabilitation Robot for hand “ReRoH” consists of a main body, an external controller and a game controller. The ReRoH installs an ER Brake to generate senses of force to wrists. We conducted characteristics tests for the brake. The results show that the output torque was 0.9 Nm at 1.4 kV input, and the response time was around 5 ms. The ReRoH also installs a Leap Motion sensor for hands coordinate. We investigated the optimal area of the sensor. By using this sensor, we suggested a new way to assess motor functions of fingers and hands.

ACS Style

Hayato Mukai; Kazuki Yamabe; Isao Abe; Takehito Kikuchi; Tetsuya Ohno. Development of Rehabilitation Robot for hand “ReRoH” for hemiplegic patients. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2017, 2017, 2A2 -H05.

AMA Style

Hayato Mukai, Kazuki Yamabe, Isao Abe, Takehito Kikuchi, Tetsuya Ohno. Development of Rehabilitation Robot for hand “ReRoH” for hemiplegic patients. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2017; 2017 ():2A2-H05.

Chicago/Turabian Style

Hayato Mukai; Kazuki Yamabe; Isao Abe; Takehito Kikuchi; Tetsuya Ohno. 2017. "Development of Rehabilitation Robot for hand “ReRoH” for hemiplegic patients." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2017, no. : 2A2-H05.

Journal article
Published: 18 October 2016 in Smart Materials and Structures
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The information on the properties of the magnetorheological fluid (MRF) in high shear rate, in particular a shear rate greater than 10 000 s−1, is important for the design of devices utilizing the MRF with very narrow fluid gaps, which are used in high-speed applications. However, very little research has been conducted on this subject. The objective of this study is to provide such information. MRF-140CG (Lord Corp.) is chosen as an example MRF. The plastic viscosity, thermal sensitivity, and durability of the fluid, especially under a shear rate greater than 10 000 s−1, are reported. The plastic viscosity is almost constant under a wide range of magnetic input. In contrast, MRF-140CG is sensitive to the shear rate; its sensitivity is relatively low at high shear rates. The thermal sensitivity shows negative values, and the effect of temperature decreases with increasing magnetic input. According to the result of the duration test at 30 000 s−1 and at a temperature of 120 °C, the lifetime dissipation energy is 5.48 MJ ml−1.

ACS Style

Takehito Kikuchi; Isao Abe; Akio Inoue; Akihiko Iwasaki; Katsuhiko Okada. Characteristics of a magnetorheological fluid in high shear rate. Smart Materials and Structures 2016, 25, 115021 .

AMA Style

Takehito Kikuchi, Isao Abe, Akio Inoue, Akihiko Iwasaki, Katsuhiko Okada. Characteristics of a magnetorheological fluid in high shear rate. Smart Materials and Structures. 2016; 25 (11):115021.

Chicago/Turabian Style

Takehito Kikuchi; Isao Abe; Akio Inoue; Akihiko Iwasaki; Katsuhiko Okada. 2016. "Characteristics of a magnetorheological fluid in high shear rate." Smart Materials and Structures 25, no. 11: 115021.

Research article
Published: 14 July 2016 in Journal of Robotics
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Movement of the knee joint of a human includes rolling and sliding. There also exist rotations in the frontal and horizontal planes. To assist the standing movement of a human, we developed a bioinspired knee joint and torque adjustment mechanism. We evaluated the motion, torque characteristics, and stress of the developed mechanism. This joint allows deep flexion of the knee with small resistance for both the user and the device. In addition, in spite of 33% error in deep flexion, the measured torque over less than 120 degrees fits the designed torque curve. We conducted evaluation tests for a human subject. The electromyogram (EMG) of musculus rectus femoris was measured during standing with or without the assistance. The result shows 30% and 63% reduction with the assistance from 100-degree and 80-degree knee angles, respectively. In addition, the proposed device reduced up to 80% of stress in the frontal plane during standing.1. IntroductionThe aging of society is rapidly progressing all over the world. According to the report of Department of Economic and Social Affairs, USA [1], the number of persons aged 60 years or more was 841 million in 2013 worldwide, and the number is expected to be 2 billion in 2050. Aging affects the overall physical functions. In particular, arthralgia (joint pain) is one of the most severe factors that prevent active lives of the aged. In Japan, the number of patients suffering from knee osteoarthritis is approximately 7 million, and the proportion continues to increase [2]. Knee joints are very important for many activities of daily living, for example, standing, walking, and climbing stairs; more than 0.5 Nm per body weight in torque is generated in the knee joint during walking [3]. The torque required in the standing action exceeds this value. The pain of knee osteoarthritis causes the losses of the range of motions, motivations of activities, and range of their activities in life.The power-assist technology was originally developed as supporting technology for military persons [4]. However, the technology is now expected to promote the active life of the aged. Commercially available power-assist wearable devices already exist, for example, MuscleSuits (INNOPHYS Co., Ltd.) [5] and HAL (CYBERDYNE Inc.) [6]; these devices are used to reduce the loads of standing or the carrying burdens of persons. Such devices use several types of actuators to generate the assistive torque and can reduce the force that directly reacts on the user’s body. However, due to the limitation of the mechanism, almost all of the devices do not support motions that require deep flexion of the knee. In addition, some devices that utilized electromagnetic motors tend to be quite heavy.In recent years, pneumatic artificial muscles have been the focus for use in power-assist system because of their high force/weight ratio [7]. A pneumatic actuator contracts with the injection of air. The core element of a pneumatic actuator is a flexible membrane closed at both ends; this rubber bag is wrapped with the sleeves of hard plastic fibers. The rubber bag inflates with the injection of air, but the deformation toward radial direction is limited by the hard sleeves. As a result, the contraction toward axial direction occurs with the injection of air [8]. The above-mentioned MuscleSuits also utilize pneumatic artificial muscles.The use of the pneumatic muscles in a power-assist system depends on the application and is mainly categorized into two types. In some devices, the pneumatic muscles are directly attached onto the surfaces of the human body, similar to clothes, for example, in the front and back of the target joint to assist its flexion and extension [9]. The other devices are combinations of the pneumatic actuators and mechanical joints, with a single-axis that is located in the outer side of the human joint [10]. The former types have an advantage that they do not require accurate alignment to the axis of the human joint. However, the inflated actuators give users the feeling of pressure. Alternatively, although the latter types of devices do not give such feelings of pressure, they must be accurately adjusted to the human joints. In addition, the above studies have not addressed the deep flexion of knee, although there are many such motions in daily life.The complicated motion of knee joint results from the restraints of motion with the related ligaments and tendons. For example, the extension of the knee includes the roll-back motion, which is a combination of rotation and sliding [11]. At the same time, the rotational axis moves, depending on the knee angle. It is difficult to adequately fit the natural motion of human knee joint only using a mechanical joint with a single-axis. Some studies that utilize a bioinspired knee mechanism can be found in the field of humanoids [12, 13] and prosthetic knees [14]. Terada et al. [15] developed a knee-motion-assist mechanism for a wearable robot with a noncircular gear and grooved cams. In this paper, we also focused on the bioinspired knee joint mechanism but utilized a different mechanism.Furthermore, during flexion of the knee joint, the femur normally has a 5–10 degrees’ abduction against the tibia, reaching up to 30 degrees during extension in some cases [16]. From the 30-degree flexion to the terminal extension, the femur rotates 5–10 degrees in inner rotation. This motion is important to lock the knee motion in the terminal extension of the knee and prevent hyperextension [11]. There are few studies of the mechanical knee joint that considered the motions in the frontal and the horizontal planes.A new mechanical knee joint that solves the above-mentioned problems is necessary for the pneumatic actuator-based power-assist suit to improve the usefulness and comfort of the suit. In this study, we propose a new bioinspired mechanism for mechanical knee joint and flexible elements that can reduce the stress from the motion with the misaligned joint.2. Target Setting2.1. Trajectory of the Axis of the Knee JointThe motion of the axis of knee joints is a combination of rotation and sliding [11]. Therefore, the rotational axis is not fixed in a point. According to the definition of the coordination system in [17] (Figure 1), the origin of the femur’s rotation in the sagittal plane with respect to the tibia’s origin moves as shown in Figure 2 during the standing motion [16]. The vertical axis of this figure shows the displacement of the superior-inferior motion of the rotational axis (positive values denote the superior positions). The horizontal axis shows the anteroposterior motion (positive values denote anterior positions). The number indicated at each plot denotes the knee angles, and the maximum extension and flexion are 0 and 150 degrees, respectively.Figure 1: Coordination system of the tibia and femur [17].Figure 2: Trajectory of the center of the femur in the sagittal plane for a Japanese male (original data are obtained from [16]).2.2. Goal of Assistive TorqueThe solid line in Figure 3 shows the average torque profile during standing for a Japanese male (40 years old, weight: 65.3 kg, and height: 171 cm) obtained from [18]. The maximum torque is 57.8 Nm at the moment of standing. The maximum torque remains flat within 80–150 degrees’ knee angle. This line is defined as a reference in this paper. In this study, we set a half of the reference as the goal of the assistive torque (Figure 5). For simplification of the structure, only extension of the knee was assisted with the device. As a result, the negative torque in the reference was translated to zero in the goal.Figure 3: Natural standing torque and assisted torque around the knee joint (original data of solid line are obtained from [18]).2.3. Force Characteristics of the Pneumatic ActuatorIn this study, we used AIR-MUSCLE (Kanda Tsushin Kogyo Co., Ltd., A300B20C20D, nominal length: 800 mm, and max. pressure: 0.6 MPa) as a power source. In addition, the maximum air pressure was defined as 0.3 MPa to allow for use of a compact compressor. This actuator is a McKibben-type artificial muscle, which can generate a compression force with air input. The force characteristics of the actuator were measured with the setup shown in Figure 4 because the actuator has individual difference in the force characteristics.Figure 4: Measurement method for determining the force characteristics of the pneumatic actuator.Figure 5: Compression rate versus compression force of the pneumatic actuator.Figure 5 shows the experimental results of the static force characteristics of this actuator. The horizontal axis shows the contraction ratio with respect to the nominal length. The vertical axis shows the compression force with each value of inner pressure and length. This actuator generates more than 750 N with 0.3 MPa at the nominal length. The force decreases with the compression rate, and it becomes zero at approximately 20% compression.3. Materials3.1. Bioinspired Knee JointWe developed a prototype of the joint mechanism by referring to the trajectory of the rotational center [19], as shown in Figure 2. Figure 6 shows the structure of the prototype, which consists of an upper part, a lower part, a wire rope, and a pulley. The upper part and the lower part move relatively with sliding and rolling. The rotational center of the upper part has a shaft that can move in a curved hole. A circular pulley is fixed with the upper part and is joined with a wire rope, one edge of which is fixed on a point of the lower part. The anteroposterior motion of the rotational axis depends on the knee angle because the shape of the sliding surface is noncircular (see the middle figure of Figure 6). The wire-pulley mechanism is also used; this mechanism defines the length between the rotational center and the fixed point (see the right figure of Figure 6). The actual motion of the mechanism is shown in Figure 7. This joint allows for deep flexion

ACS Style

Takehito Kikuchi; Kohei Sakai; Isao Abe. Bioinspired Knee Joint for a Power-Assist Suit. Journal of Robotics 2016, 2016, 1 -8.

AMA Style

Takehito Kikuchi, Kohei Sakai, Isao Abe. Bioinspired Knee Joint for a Power-Assist Suit. Journal of Robotics. 2016; 2016 ():1-8.

Chicago/Turabian Style

Takehito Kikuchi; Kohei Sakai; Isao Abe. 2016. "Bioinspired Knee Joint for a Power-Assist Suit." Journal of Robotics 2016, no. : 1-8.

Research article
Published: 24 July 2015 in Journal of Intelligent Material Systems and Structures
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Haptics is a tactile feedback technology that recreates the sense of touch to the user by applying forces, vibrations, or motions. Haptic devices should have a high performance in their output characteristics, for example, low friction in off-state, constant force with constant input, and quick response with dynamic input, in order to generate a sufficient sense of touch to human skin. We have focused on rapid response of magnetorheological fluid and decided to use it as the working material of the haptic device. There are several types of magnetorheological fluids available, and the effects of the different types of magnetorheological fluids on the response time of the haptic device have not yet been reported. The objective of this study is to experimentally investigate the response time of a magnetorheological fluid–based haptic device with two different types of magnetorheological fluids. We originally developed a single-disc type magnetorheological fluid–based haptic device, and its response time was investigated with two types of magnetorheological fluids. We set three experimental conditions with regard to the fluid gap and rotational velocity. We modeled the haptic devices as a classic first-order lag system, and the time constant of this system was assumed to be representative of the response time of the haptic device. According to the results, the response times of a sample tend to be smaller with the narrow gap (0.1 mm), whereas those of the other tend to be smaller with the large gap (0.5 mm). In addition, the response time is non-dimensioned and investigated with Mason number.

ACS Style

Takehito Kikuchi; Junichi Noma; Syuichi Akaiwa; Yuya Ueshima. Response time of magnetorheological fluid–based haptic device. Journal of Intelligent Material Systems and Structures 2015, 27, 859 -865.

AMA Style

Takehito Kikuchi, Junichi Noma, Syuichi Akaiwa, Yuya Ueshima. Response time of magnetorheological fluid–based haptic device. Journal of Intelligent Material Systems and Structures. 2015; 27 (7):859-865.

Chicago/Turabian Style

Takehito Kikuchi; Junichi Noma; Syuichi Akaiwa; Yuya Ueshima. 2015. "Response time of magnetorheological fluid–based haptic device." Journal of Intelligent Material Systems and Structures 27, no. 7: 859-865.

Conference paper
Published: 01 January 2015 in The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)
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ACS Style

Keisuke Mori; Isao Abe; Takehito Kikuchi. 2A2-I02 Improvement of presence for VR bicycle system and its evaluation. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2015, 2015, 1 .

AMA Style

Keisuke Mori, Isao Abe, Takehito Kikuchi. 2A2-I02 Improvement of presence for VR bicycle system and its evaluation. The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec). 2015; 2015 ():1.

Chicago/Turabian Style

Keisuke Mori; Isao Abe; Takehito Kikuchi. 2015. "2A2-I02 Improvement of presence for VR bicycle system and its evaluation." The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2015, no. : 1.

Conference paper
Published: 01 January 2014 in The Proceedings of Conference of Kyushu Branch
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ACS Style

Kohei Sakai; Isao Abe; Takehito Kikuchi. 3F1 Study on motion control of pneumatic artificial muscle for patient-like robot. The Proceedings of Conference of Kyushu Branch 2014, 2014, 1 .

AMA Style

Kohei Sakai, Isao Abe, Takehito Kikuchi. 3F1 Study on motion control of pneumatic artificial muscle for patient-like robot. The Proceedings of Conference of Kyushu Branch. 2014; 2014 ():1.

Chicago/Turabian Style

Kohei Sakai; Isao Abe; Takehito Kikuchi. 2014. "3F1 Study on motion control of pneumatic artificial muscle for patient-like robot." The Proceedings of Conference of Kyushu Branch 2014, no. : 1.