Hiroshi YOKOI (横井 浩史)

Offer Organization: 日本学術振興会, System Name: 科学研究費助成事業 基盤研究(B), Category: 基盤研究(B), Fund Type: -, Overall Grant Amount: - (direct: 13600000, indirect: 4080000)
本研究では，自己身体として身体認知を可能にするサイボーグ義手の開発とその方法論を構築し，生来身体に近づいた自然な操作感を実現する次世代の実用的なサイボーグ義手の実現を目的とする．2021年度の成果は以下の4点である．
a)身体認知を促進させる体性感覚フィードバックの実現のために，義手を装着するソケット内に設置可能な超薄型多点振動シートを開発した．形状記憶合金を薄板に配置し，高速で伸縮させ薄板を振動させることで，厚さ2mm程度の柔軟な振動子を実現した．これにより，従来の10mm程度の振動子と同様の刺激・認識精度を実現した．
b)操作集中や操作負担を軽減させる制御手法を実現するために，義手ハンドに超小型距離画像センサを配置し，距離画像を用いて深層学習により物体形状を認識し把持姿勢を決定し，筋電で把持動作の決定を行う手法を構築した．これにより日常生活動作の85%程度をカバーできる3種の把持姿勢，2種の手首姿勢に関して90%以上の識別率で手指動作の識別可能にし不自然な操作力が必要がなく操作可能となった．
c)常時装着が可能な多自由度サイボーグ義手の義手装飾グローブの開発を行った．当初予定より開発の柔軟度を向上させるため，新たにゴムライク樹脂の3次元造形機を導入し，皮膚程度の柔軟さをもつ装飾グローブの造形を可能にした．さらに生体計測用ゴム電極を用いた超薄型の筋電センサバンドを開発し皮膚への密着性を高め安定的な信号計測を可能にした．手先重量300g，総重量1kg程度の上腕義手(手指自由度4，手首1，肘1)を開発した．4名の上腕切断者用の義手を準備をし，2022年度の身体認知の検証を行うための準備を行った．
d)義手の長期使用における身体認知への影響を調査するための準備として，東海大学医学部，成育医療研究センターと連携し，筋電義手の被験者を募集し，参加同意や上肢機能の臨床評価指標を決定した．

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3300000, indirect: 990000)
Surface electromyography (sEMG) has been widely investigated as a biological signal from which motion intentions can be recognized to control prosthetic hands. The availability and quality of sEMG can limit the usability and intuitiveness of advanced prosthetic hands that can restore most necessary hand movements. This study introduces force myography (FMG) as a supplementary signal and develops a hybrid sensor to measure sEMG and FMG signals simultaneously. Furthermore, a layer-fusion convolutional neural network (CNN) was proposed to analyze the sEMG and FMG signals. The recognition results of hand motion showed a significantly improved classification accuracy (CA) of the hybrid sEMG and FMG with respect to individual modality due to the rubustness of FMG. The FMG-assisted sEMG sensing approach can effectively offer great potential in the clinical application of sophisticated prosthetic hands without increasing burden to the user.

Offer Organization: 日本学術振興会, System Name: 科学研究費助成事業 基盤研究(A), Category: 基盤研究(A), Fund Type: -, Overall Grant Amount: - (direct: 33500000, indirect: 10050000)
本研究は，前腕切断者用の筋電義手として，自由度の高い運動能力と感覚の代替機能の実現を目指して，指先の触圧感覚と関節角のフィードバック機構を有する5指ハンドの開発を行い，筋電制御システムを利用して，切断者の手指動作の再建の課題に挑戦する．
課題は，メカ開発とセンサグローブ開発の2項目からなる．
メカ開発では，ワイヤー干渉駆動法を用いて軽量・多自由度・高出力を有する5指ロボットハンドを試作し，性能評価を通して改良し，筋電義手に適用可能な設計法を明らかにすることを目指した．2021年度においては，3名の成人前腕切断者に，試作した5指駆動型筋電義手を適用し，フィールドテストを行った．期間中3回のフィールドテスト評価では，自由度義手との性能差を，BBT（Box and Block Test）及びCarroll test等の評価試験によって比較し，有用性を評価した．
当多自由度義手は，国内2例目の筋電義手として，2022年3月31日，厚生労働省補装具完成用部品に指定された．
センサグローブ開発においては，導電性シリコンを応用することにより，指先の触圧と関節角を計測し，これを振動子を用いて断端部ソケットに伝達することを目的として，開発を進めた．2020年度においては，さらに，感覚のフィードバックの方法として視覚への映像変化として情報提示を行う方法を開発し，前述の触覚と聴覚へのフィードバックとのパフォーマンス比較実験を行った．患者への触覚のフィードバック方法として申請当初はボイスコイルによる振動フィードバックを検討していたが，2021年度に再検討し，フィードバックの呈示装置として骨伝導イヤホンを採用することとし，有効性検証のため，聴覚刺激を行いながら日常生活音を聞き応答する二重課題法を行い，人の囁き声に当たる30～40dBの小さな音に応答できること，これが日常生活を阻害しないことを明らかにした．

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3500000, indirect: 1050000)
The minimum length of the HALS incision is 50 mm. Also, the hands and fingers of the operators are at risk of burn injury and the range of hand movement is restricted. To address these shortcomings of HALS, we have studied a 5-finger robot hand with a similar size to a child’s hand and the functionality of a normal hand. In collaboration with an engineering group, we have investigated whether such a hand could be developed to perform robotic HALS clinically. We have been granted several patents for a modified robot hand system that was originally developed for an electronic hand. The robot hand can perform the surgical procedures required for HALS and folds vertically at the palm to reduce its size for insertion through the incision. Furthermore, we are developing an exoskeleton signaling system with pressure sensors incorporated into the tips of the robot fingers to provide pseudo-tactile sensation for the surgeon.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Young Scientists (B), Fund Type: -, Overall Grant Amount: - (direct: 3200000, indirect: 960000)
In this study, we aimed to model a mechanism of voluntary control of human multi-muscle, and apply it for controlling EMG shoulder disarticulation prosthesis. First, a notion of voluntary control was introduced to the framework of muscle synergy analysis. Then, our experiments demonstrated that voluntarily activatable muscle synergies could be extracted by using an appropriate index. It was also suggested that the muscle synergy is not a minimum unit of voluntary muscle control. Moreover, we applied the notion of the synergy freezing degrees of freedom to the EMG shoulder disarticulation prosthesis system so as to control its robot-arm movements by low degrees of freedom input. As a result, both-shoulder amputee user could use our developed EMG shoulder disarticulation prosthesis to pick an object and place on it. Above results showed the usability of our proposed notion “humanize-robotics.”

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3600000, indirect: 1080000)
An amputated nerve transferred to a nearby muscle produces a detectable electromyographic signal corresponding to the transferred nerve; this technique is known as targeted muscle reinnervation (TMR). It is optimal to select and transfer each motor fascicle to achieve highly developed myoelectric arms with multiple degrees-of-freedom motion. Each median nerve fascicle was transferred to the long head branch of the biceps or the brachialis branch, while the short head branch of the biceps was retained for elbow flexion. Each radial nerve fascicle was transferred to the medial or lateral head branch of the triceps, while the long head branch of the triceps was retained for elbow extension. Functional and electrophysiological improvement was noted, with marked improvement in the identification rate for each digit, forearm, and elbow motion after the selective nerve transfers. More selective nerve transfers may be required for the development of prostheses with multiple degrees of freedom.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3700000, indirect: 1110000)
sEMG (Surface Electromyography) is the electric activity of groups of muscles measured with electrodes on the skin surface. Since it reflects motion intentions, sEMG has been studied as a signal to control welfare machines. This study investigated the electrodes, measurement method, and selection of multi-channel sEMG signals. Soft and wearable sEMG electrodes were developed with conductive polymers and conductive silicon. The relation between bioelectric characteristics and the quality of sEMG was elucidated. And a multi-channel sEMG measurement system was developed and validated with healthy subjects and amputees.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research, Category: Grant-in-Aid for Challenging Exploratory Research, Fund Type: -, Overall Grant Amount: - (direct: 2700000, indirect: 810000)
Surface electrodes are required to measure the EMG (Electromyography) signals for the control of myoelectric prosthetic hands. This study developed conductive silicon by mixing silicon with aggregative carbon black. The conductive silicon was applied to metallic non-woven fabric to create materials for the electrodes. Since the electrodes are supposed to be used between the skin and the socket, the influence of force to the quality of the EMG signal was investigated. The electrodes were encapsulated in insulating silicon to be applicable to circumstances with sweat or water. Furthermore, a pressure-sensitive sensor was developed with the conductive silicon, which can be integrated into the prosthetic hand to provide sensory function.