Kazunori Ogawa

Development of a pneumatic artificial muscle driven by low pressure and its application to the unplugged powered suit

Abstract Assistive suits reduce human muscle effort by improving human motion. However, most assistive suits are bulky, are expensive, need external power sources, and are impractical to carry everywhere. We present the development of the pneumatic gel muscle, which can be actuated by very low air pressure, and its characteristics by comparing with a commercially available artificial muscle. We also discuss the design of an unplugged powered suit for walking assist that unloads the muscle effort using the pneumatic gel muscle, demonstrating that assistive forces can be applied without the use of a compressor or air tanks. We performed experiments to measure characteristics of the pneumatic gel muscle, such as the actuation and applied force, for various pressure ranges. We measured surface EMG of the lower limb with and without an unplugged powered suit to identify the unloading effect of the suit.

Pneumatic-type dynamic traction and flexion splint for treating patients with extension contracture of the metacarpophalangeal joint

Background: Collateral ligament shortening causes extension contractures of the metacarpophalangeal joint, and dynamic flexion splinting has been widely used to treat these contractures; however, there are various problems with these approaches. We developed a novel, pneumatic-type dynamic traction and flexion splint to solve these problems. Case description and methods: A total of 25 fingers were treated with the dynamic traction and flexion splint for 8 weeks. Every 2 weeks, the average metacarpophalangeal joint flexion angle, total active motion, grasp strength, and pain scores were assessed. Findings and outcomes: The finger flexion angle was significantly greater at the final evaluation, starting after 6 weeks of treatment (p < 0.05), than prior to treatment. Similarly, the total active motion results improved significantly over 8 weeks. Conclusions: Our results show that use of the dynamic traction and flexion splint improves patient finger functioning and flexural angle. Clinical relevance The dynamic traction and flexion (DTF) splint appears to be effective for treating patients.

Reinforced Suit Using Low Pressure Driven Artificial Muscles For Baseball Bat Swing

This paper proposes an assistive device to augment the sports activity. This experiment presents a bat swing augmentation suit for baseball that can provide automatically the assistive timing required to improve the performance of the user, this action is determined by the system. To generate the operation at the appropriate timing, an acceleration sensor, electric valves, and a microcomputer are attached on the suit. We conduct the experiment to confirm the performance of the suit by measuring the swinging speed. The experimental results showed that the device can improve the swinging speed of experienced subjects about 3 km/h.

Evaluation of unplugged powered suit with pneumatic gel muscles

Assistive suits are useful in situations such as injury, muscle fatigue, stressful work environment in factories and are also useful for different age groups in these situations. In our research, we use pneumatic gel muscles (PGM) to develop assistive suit to enhance walking gait experience. We focused on assisting the swing phase of the gait cycle as it accounts for higher metabolic costs during gait. The pneumatic gel muscles are actuated with small pumps fitted in the shoe of the contralateral foot of assisted leg. By doing this we can take advantage of dual support phase in gait cycle and provide required power for PGM. This process provides assisting force during swing phase and thus helps user with improved walking experience. To test the effectiveness of this suit we identified muscles with reduced force and activation for assisted gait using Opensim simulation and measured EMG for these muscles during experiment. Similar patterns in both simulations and experimental results were observed.

A soft exoskeleton suit to reduce muscle fatigue with pneumatic artificial muscles

A major issue at work sites corresponds to aging workers, and the associated back pain. In this research, we develop an assistive suit with light-weight and flexible pneumatic rubber artificial muscles to reduce muscle load. Two assist forces are designed to control the artificial muscles with PWM-control based on: 1) flexion angle, and 2) estimated torque of the hip joint. The experimental results show that the proposed suit can reduce muscle activity during bending and stretching motions.

Supporting Effects on Muscles of a Motion Assistive Wear Depending on the Fixture Position

1.はじめに 老化・疲労の影響により筋力が低下すると,怪 我・事故が発生する可能性が大きくなる.そこで 筋力を補助する役割を果たすサポーターが必要と なる.近年,サポートウェアが盛んに開発されて おり,さまざまな方法でサポート効果の計測が行 われている.従来研究では,トルクや筋電位, 力センサを計測することによりサポートウェアの 評価が行われているが,個人の骨格や筋肉量,体 型が,ウェアのサポート効果にどのように影響し ているのかは分かっていない.そこで本研究では、 動作補助パーツを組み込んだ筋骨格シミュレー ションにより補助効果を定量的に評価し,体型や 取付位置の違いが補助効果に与える影響を評価す るための手法について説明する. 2.動作補助パーツモデル作成 本研究では,ダイヤ工業(株)が市販している 機能性アンダーウェアDARWING における運動補助 効果の検証を行う.DARWING の表層部には伸縮性 素材(動作補助パーツ)が使用されており,バネ のように働くことで装着者の筋負担を軽減する効 果があるとされる.しかし着用する人の体格が変 わると動作補助パーツの身体に対する取付位置が 変わり,筋に対する補助効果に影響が出る可能性 がある.そこで動作補助パーツの性質をモデル化 し,それを様々な体格の筋骨格モデルに取り付け たときに既存の筋肉の活動にどのような影響が出 るのかを調べる. 図1は,荷重に対する動作補助パーツの伸長量 の特性と,計算の簡略化のためその特性を近似し たモデルの特性を示したものである.シミュレー ションによる評価を行うために図2に示す DARWINGの動作補助パーツの形状と特性を模した 動作補助パーツモデルを作成した. 図1 動作補助パーツとモデルの対荷重特性

Unplugged Powered Suit with Pneumatic Gel Muscles

Assistive suits are useful in case of injury or muscle fatigue or due to aging. To support such conditions, we develop the unplugged assistive suit using low air pressure actuated pneumatic artificial muscles (PAMs). In demonstration we show the ability to actuate low power PAMs with the help of a shoe with air pumping capability. Most PAMs require an external source of energy i.e. an electric air compressor to operate, but in our proposed model we use human motions as a tool to generate air pressure which result in assisting motions of a leg in the swing motion by giving sense of assistive feeling to a human. This is also verified by analyzing the experimental results.