TED日本語 - トッド・クイケン: 「感覚を持つ」義手



TED日本語 - トッド・クイケン: 「感覚を持つ」義手

TED Talks

A prosthetic arm that "feels"
Todd Kuiken




So today, I would like to talk with you about bionics, which is the popular term for the science of replacing part of a living organism with a mechatronic device, or a robot. It is essentially the stuff of life meets machine. And specifically, I'd like to talk with you about how bionics is evolving for people with arm amputations.

This is our motivation. Arm amputation causes a huge disability. I mean, the functional impairment is clear. Our hands are amazing instruments. And when you lose one, far less both, it's a lot harder to do the things we physically need to do. There's also a huge emotional impact. And actually, I spend as much of my time in clinic dealing with the emotional adjustment of patients as with the physical disability. And finally, there's a profound social impact. We talk with our hands. We greet with our hands. And we interact with the physical world with our hands. And when they're missing, it's a barrier. Arm amputation is usually caused by trauma, with things like industrial accidents, motor vehicle collisions or, very poignantly, war. There are also some children who are born without arms, called congenital limb deficiency.

Unfortunately, we don't do great with upper-limb prosthetics. There are two general types. They're called body-powered prostheses, which were invented just after the Civil War, refined in World War I and World War II. Here you see a patent for an arm in 1912. It's not a lot different than the one you see on my patient. They work by harnessing shoulder power. So when you squish your shoulders, they pull on a bicycle cable. And that bicycle cable can open or close a hand or a hook or bend an elbow. And we still use them commonly, because they're very robust and relatively simple devices.

The state of the art is what we call myoelectric prostheses. These are motorized devices that are controlled by little electrical signals from your muscle. Every time you contract a muscle, it emits a little electricity that you can record with antennae or electrodes and use that to operate the motorized prosthesis. They work pretty well for people who have just lost their hand, because your hand muscles are still there. You squeeze your hand, these muscles contract. You open it, these muscles contract. So it's intuitive, and it works pretty well.

Well how about with higher levels of amputation? Now you've lost your arm above the elbow. You're missing not only these muscles, but your hand and your elbow too. What do you do? Well our patients have to use very code-y systems of using just their arm muscles to operate robotic limbs. We have robotic limbs. There are several available on the market, and here you see a few. They contain just a hand that will open and close, a wrist rotator and an elbow. There's no other functions. If they did, how would we tell them what to do?

We built our own arm at the Rehab Institute of Chicago where we've added some wrist flexion and shoulder joints to get up to six motors, or six degrees of freedom. And we've had the opportunity to work with some very advanced arms that were funded by the U.S. military, using these prototypes, that had up to 10 different degrees of freedom including movable hands. But at the end of the day, how do we tell these robotic arms what to do? How do we control them? Well we need a neural interface, a way to connect to our nervous system or our thought processes so that it's intuitive, it's natural, like for you and I.

Well the body works by starting a motor command in your brain, going down your spinal cord, out the nerves and to your periphery. And your sensation's the exact opposite. You touch yourself, there's a stimulus that comes up those very same nerves back up to your brain. When you lose your arm, that nervous system still works. Those nerves can put out command signals. And if I tap the nerve ending on a World War II vet, he'll still feel his missing hand. So you might say, let's go to the brain and put something in the brain to record signals, or in the end of the peripheral nerve and record them there. And these are very exciting research areas, but it's really, really hard. You have to put in hundreds of microscopic wires to record from little tiny individual neurons -- ordinary fibers that put out tiny signals that are microvolts. And it's just too hard to use now and for my patients today.

So we developed a different approach. We're using a biological amplifier to amplify these nerve signals -- muscles. Muscles will amplify the nerve signals about a thousand-fold, so that we can record them from on top of the skin, like you saw earlier. So our approach is something we call targeted reinnervation. Imagine, with somebody who's lost their whole arm, we still have four major nerves that go down your arm. And we take the nerve away from your chest muscle and let these nerves grow into it. Now you think, "Close hand," and a little section of your chest contracts. You think, "Bend elbow," a different section contracts. And we can use electrodes or antennae to pick that up and tell the arm to move. That's the idea.

So this is the first man that we tried it on. His name is Jesse Sullivan. He's just a saint of a man -- 54-year-old lineman who touched the wrong wire and had both of his arms burnt so badly they had to be amputated at the shoulder. Jesse came to us at the RIC to be fit with these state-of-the-art devices, and here you see them. I'm still using that old technology with a bicycle cable on his right side. And he picks which joint he wants to move with those chin switches. On the left side he's got a modern motorized prosthesis with those three joints, and he operates little pads in his shoulder that he touches to make the arm go. And Jesse's a good crane operator, and he did okay by our standards.

He also required a revision surgery on his chest. And that gave us the opportunity to do targeted reinnervation. So my colleague, Dr. Greg Dumanian, did the surgery. First, we cut away the nerve to his own muscle, then we took the arm nerves and just kind of had them shift down onto his chest and closed him up. And after about three months, the nerves grew in a little bit and we could get a twitch. And after six months, the nerves grew in well, and you could see strong contractions. And this is what it looks like. This is what happens when Jesse thinks open and close his hand, or bend or straighten your elbow. You can see the movements on his chest, and those little hash marks are where we put our antennae, or electrodes. And I challenge anybody in the room to make their chest go like this. His brain is thinking about his arm. He has not learned how to do this with the chest. There is not a learning process. That's why it's intuitive.

So here's Jesse in our first little test with him. On the left-hand side, you see his original prosthesis, and he's using those switches to move little blocks from one box to the other. He's had that arm for about 20 months, so he's pretty good with it. On the right side,two months after we fit him with his targeted reinnervation prosthesis -- which, by the way, is the same physical arm, just programmed a little different -- you can see that he's much faster and much smoother as he moves these little blocks. And we're only able to use three of the signals at this time.

Then we had one of those little surprises in science. So we're all motivated to get motor commands to drive robotic arms. And after a few months, you touch Jesse on his chest, and he felt his missing hand. His hand sensation grew into his chest again probably because we had also taken away a lot of fat, so the skin was right down to the muscle and deinnervated, if you would, his skin. So you touch Jesse here, he feels his thumb; you touch it here, he feels his pinky. He feels light touch down to one gram of force. He feels hot, cold, sharp, dull, all in his missing hand, or both his hand and his chest, but he can attend to either. So this is really exciting for us, because now we have a portal, a portal, or a way to potentially give back sensation, so that he might feel what he touches with his prosthetic hand. Imagine sensors in the hand coming up and pressing on this new hand skin. So it was very exciting.

We've also gone on with what was initially our primary population of people with above-the-elbow amputations. And here we deinnervate, or cut the nerve away, just from little segments of muscle and leave others alone that give us our up-down signals and two others that will give us a hand open and close signal. This was one of our first patients, Chris. You see him with his original device on the left there after eight months of use, and on the right, it is two months. He's about four or five times as fast with this simple little performance metric.

All right. So one of the best parts of my job is working with really great patients who are also our research collaborators. And we're fortunate today to have Amanda Kitts come and join us. Please welcome Amanda Kitts.


So Amanda, would you please tell us how you lost your arm?

Amanda Kitts: Sure. In 2006, I had a car accident. And I was driving home from work, and a truck was coming the opposite direction, came over into my lane, ran over the top of my car and his axle tore my arm off.

Todd Kuiken: Okay, so after your amputation, you healed up. And you've got one of these conventional arms. Can you tell us how it worked?

AK: Well, it was a little difficult, because all I had to work with was a bicep and a tricep. So for the simple little things like picking something up, I would have to bend my elbow, and then I would have to cocontract to get it to change modes. When I did that, I had to use my bicep to get the hand to close, use my tricep to get it to open, cocontract again to get the elbow to work again.

TK: So it was a little slow?

AK: A little slow, and it was just hard to work. You had to concentrate a whole lot.

TK: Okay, so I think about nine months later that you had the targeted reinnervation surgery, took six more months to have all the reinnervation. Then we fit her with a prosthesis. And how did that work for you?

AK: It works good. I was able to use my elbow and my hand simultaneously. I could work them just by my thoughts. So I didn't have to do any of the cocontracting and all that.

TK: A little faster?

AK: A little faster. And much more easy, much more natural.

TK: Okay, this was my goal. For 20 years, my goal was to let somebody [ be ] able to use their elbow and hand in an intuitive way and at the same time. And we now have over 50 patients around the world who have had this surgery, including over a dozen of our wounded warriors in the U.S. armed services. The success rate of the nerve transfers is very high. It's like 96 percent. Because we're putting a big fat nerve onto a little piece of muscle. And it provides intuitive control. Our functional testing, those little tests, all show that they're a lot quicker and a lot easier. And the most important thing is our patients have appreciated it.

So that was all very exciting. But we want to do better. There's a lot of information in those nerve signals, and we wanted to get more. You can move each finger. You can move your thumb, your wrist. Can we get more out of it? So we did some experiments where we saturated our poor patients with zillions of electrodes and then had them try to do two dozen different tasks -- from wiggling a finger to moving a whole arm to reaching for something -- and recorded this data. And then we used some algorithms that are a lot like speech recognition algorithms, called pattern recognition. See.


And here you can see, on Jesse's chest, when he just tried to do three different things, you can see three different patterns. But I can't put in an electrode and say, "Go there." So we collaborated with our colleagues in University of New Brunswick, came up with this algorithm control, which Amanda can now demonstrate.

AK: So I have the elbow that goes up and down. I have the wrist rotation that goes -- and it can go all the way around. And I have the wrist flexion and extension. And I also have the hand closed and open.

TK: Thank you, Amanda. Now this is a research arm, but it's made out of commercial components from here down and a few that I've borrowed from around the world. It's about seven pounds, which is probably about what my arm would weigh if I lost it right here. Obviously, that's heavy for Amanda. And in fact, it feels even heavier, because it's not glued on the same. She's carrying all the weight through harnesses.

So the exciting part isn't so much the mechatronics, but the control. So we've developed a small microcomputer that is blinking somewhere behind her back and is operating this all by the way she trains it to use her individual muscle signals. So Amanda, when you first started using this arm, how long did it take to use it?

AK: It took just about probably three to four hours to get it to train. I had to hook it up to a computer, so I couldn't just train it anywhere. So if it stopped working, I just had to take it off. So now it's able to train with just this little piece on the back. I can wear it around. If it stops working for some reason, I can retrain it. Takes about a minute.

TK: So we're really excited, because now we're getting to a clinically practical device. And that's where our goal is -- to have something clinically pragmatic to wear. We've also had Amanda able to use some of our more advanced arms that I showed you earlier. Here's Amanda using an arm made by DEKA Research Corporation. And I believe Dean Kamen presented it at TED a few years ago. So Amanda, you can see, has really good control. It's all the pattern recognition. And it now has a hand that can do different grasps. What we do is have the patient go all the way open and think, "What hand grasp pattern do I want?" It goes into that mode, and then you can do up to five or six different hand grasps with this hand. Amanda, how many were you able to do with the DEKA arm?

AK: I was able to get four. I had the key grip, I had a chuck grip, I had a power grasp and I had a fine pinch. But my favorite one was just when the hand was open, because I work with kids, and so all the time you're clapping and singing, so I was able to do that again, which was really good.

TK: That hand's not so good for clapping.

AK: Can't clap with this one.

TK: All right. So that's exciting on where we may go with the better mechatronics, if we make them good enough to put out on the market and use in a field trial. I want you to watch closely.

(Video) Claudia: Oooooh!

TK: That's Claudia, and that was the first time she got to feel sensation through her prosthetic. She had a little sensor at the end of her prosthesis that then she rubbed over different surfaces, and she could feel different textures of sandpaper, different grits, ribbon cable, as it pushed on her reinnervated hand skin. She said that when she just ran it across the table, it felt like her finger was rocking. So that's an exciting laboratory experiment on how to give back, potentially, some skin sensation.

But here's another video that shows some of our challenges. This is Jesse, and he's squeezing a foam toy. And the harder he squeezes -- you see a little black thing in the middle that's pushing on his skin proportional to how hard he squeezes. But look at all the electrodes around it. I've got a real estate problem. You're supposed to put a bunch of these things on there, but our little motor's making all kinds of noise right next to my electrodes. So we're really challenged on what we're doing there.

The future is bright. We're excited about where we are and a lot of things we want to do. So for example, one is to get rid of my real estate problem and get better signals. We want to develop these little tiny capsules about the size of a piece of risotto that we can put into the muscles and telemeter out the EMG signals, so that it's not worrying about electrode contact. And we can have the real estate open to try more sensation feedback. We want to build a better arm. This arm -- they're always made for the 50th percentile male -- which means they're too big for five-eighths of the world. So rather than a super strong or super fast arm, we're making an arm that is -- we're starting with, the 25th percentile female -- that will have a hand that wraps around, opens all the way,two degrees of freedom in the wrist and an elbow. So it'll be the smallest and lightest and the smartest arm ever made. Once we can do it that small, it's a lot easier making them bigger.

So those are just some of our goals. And we really appreciate you all being here today. I'd like to tell you a little bit about the dark side, with yesterday's theme. So Amanda came jet-lagged, she's using the arm, and everything goes wrong. There was a computer spook, a broken wire, a converter that sparked. We took out a whole circuit in the hotel and just about put on the fire alarm. And none of those problems could I have dealt with, but I have a really bright research team. And thankfully Dr. Annie Simon was with us and worked really hard yesterday to fix it. That's science. And fortunately, it worked today.

So thank you very much.


本日はみなさんに 生体工学 つまり身体の一部を メカトロニクス機器やロボットで置き換えるという 科学分野についてお話ししようと思います これは正に 生体と機械の融合です 特に 腕を失った人の為に 生体工学が どう進歩しているかをお話しします

我々の研究動機です 腕を失うとは大変なことです 単純な不便さは勿論でしょう 手は素晴らしい道具です 片手を失っただけで 日常的に必要とされる 身体的行為が難しくなります そして大きな精神的ダメージ 私の診療室では 身体的不自由さと 同じくらい 精神的ダメージの治療にも 時間をかけています 社交上の問題もあります 我々は手で話し 手で挨拶をし 手で外界とやりとりをします 手がなくなることは 障害を意味します 腕の切断の多くは 工場事故や交通事故 そして悲しくも 戦争による外傷の結果です 生まれつき腕のない子もいます 先天性四肢欠損です

残念ながら義手の製作は 困難を極めています 義手には2種類あります こちらは身体操作型義手といって 南北戦争直後に発明され 第1・2次世界大戦中に改良されました これが1912年の 特許申請書です 現在の義手と そう違いはありません 肩の筋肉で制御するものです 肩をすぼめるとケーブルが引かれ 手やフックを開いたり閉じたり 肘を動かせます この義手は今でも使われています とても頑丈で単純な構造ですからね

最先端のものは 筋電義手という義手です 筋肉からのわずかな 電気信号により モーター駆動される義手です 筋肉を収縮させる時 わずかな電気信号が流れ それを電極やアンテナで読み取り 義手の操作に用いるのです 手を失ったばかりの人の場合 この義手をとても上手く操作します 手の筋肉がまだ残っていますから 手をすぼめればこの筋肉が収縮し 手をひらけばこの筋肉が収縮し 直感的に上手に使うことができます

しかしもっと上部で 腕の大半を切断するとどうでしょう この筋肉だけでなく 手と肘そのものがありません どうしましょう? そのような患者さんは 腕の筋肉だけで ロボット義手を動かす 技術を要する方法をとります ロボット義手ということです このように様々な種類があります 開閉する手と 回転する手首と 肘があります 機能はそれだけです 機能を増やしても制御方法がありません

そこで シカゴリハビリテーション研究所(RIC)では 手首の屈曲と 肩の関節を加え 6つのモーターで 6自由度を持つ試作品を作りました さらに我々は米軍から研究費を得て開発された 可動式の手を持ち 最大10の自由度を持つ 進歩した義手を 使うことができました しかし結局どう義手に 命令を伝えたものでしょうか どう操作すれば良いのでしょう? その為には神経系あるいは思考過程と 繋ぐことで身体の一部の様に 直感的かつ自然に操作できる 神経インタフェースが 必要なのです

脳から発する運動命令は 脊髄を伝わり末梢神経をとおって 末梢に伝わります 感覚はその反対です 刺激は全く同じ神経を逆に辿り 脳に伝えます 腕を失ってもまだ神経系は働きます まだ脳の指令を送ることができます そして退役軍人が失った 腕の端の神経を触ると 彼はまだ手を感じるのです それならば脳を開けて 脳内に何かを埋め込み 信号を記録したり あるいは末梢神経の末端で 信号を記録したりしてみよう 確かにそういう研究もありますが これは恐ろしく難しいのです 数百の微小電極を埋め込み 信号を発する小さな個々のニューロン - 普通の神経線維 -から マイクロボルト単位の 信号を読み取る 必要があります これは現在 技術的に 難度が高過ぎます

そこで違う方法を考えました 神経信号を増幅する生体機能 つまり筋肉を使えば良いのです 筋肉は神経信号を 数千倍に増幅するので 先程お見せしたように 皮膚の上からでも 信号が取れます 特定領域への神経支配再確立とでも言えましょう 腕を失っても (腕を支配する)4つの主要な神経が まだ残っている患者を 想像してみて下さい その患者の胸筋から神経を取り除き 代わりに腕の神経を埋め込みます 「手を握ろう」と考えれば胸の一部が収縮し 「肘を曲げよう」と考えれば 胸の別の場所が収縮します その動きを電極やアンテナで 読み取り義手を操作すればいい これが我々のアイデアです

この義手を初めて試した患者です ジェシー・サリヴァンという名で とても穏やかな方です 架線作業中に触る電線を間違え 両の手に重度の火傷を負い 肩から先を切断しました そして最先端の義手を試すため RICの私たちのところにやって来ました 右腕はケーブル操作する 旧型の義手を使っています 動かす関節はアゴのスイッチで選びます 左では3つの関節を持つ モーター駆動の義手で 肩のパッドで動かしています 腕の操作に使うためです ジェシーは操縦が上手く 私たちも満足でした

加えて彼は胸の追加手術も必要になりました これをよい機会に我々は 特定領域への神経支配再確立手術を行いました 手術を行ったのは 同僚のグレッグ ドゥマニアン博士です まず胸の神経を取り除き 腕の神経を取り出し それを胸に植え込んで 傷口を塞ぎました 3ヶ月後には神経も少し伸び 胸をピクピク動かせるようになり 6ヶ月後には神経も十分に伸びて 強い収縮も可能になりました このような感じです ジェシーが手を開閉させようと思うと この動作がおきます 肘を屈曲したり伸ばそうと思うと 胸がこう動きます この小さなしるしは アンテナや電極の位置です こんな風に胸を動かせる人が もし会場にいれば教えてください 彼の脳は腕のことを考えています 胸をこんな風に動かす方法を 学んだわけではありません 学習過程はありません 直感的なのです

これが最初の動作テストです 左側は元の義手です スイッチを使って 積み木を ひとつの箱からもう一つの箱へ移しています 20ヶ月も使用した義手はよくなじんでいます 右側は私たちの 「特定領域への神経支配再確立」を使って 2ヶ月目の映像です 機器としては同じ義手で 制御ソフトが違うだけですが 動作は明らかに速く スムーズに積み木を移しています この時点で3つの信号を使っているだけです

ここで驚くべき科学的発見がありました 私たちはロボット義手を操作するための 運動指令を得ようとしていた訳ですが 数ヶ月後にジェシーの 胸に触れると 彼は 失った手を感じました 手の感覚が胸に戻ったのです 手術で脂肪を取り去ったので 筋肉と皮膚が近づき 以前あった神経支配を取り除いたのでしょう ここを触れば親指を感じ ここを触れば小指です 1 gほどの小さな 力でも感じます 熱さ、冷たさ、鋭さ、鈍さ 全てを失われた手で感じます 胸の感覚も残っていますが 意識できるのは一方です これはとても面白いことです なぜなら これは感覚の再現に繋がる可能性があり あるいは末梢神経の末端で 触れたものを感じる義手の製作にも 繋がる可能性があるからです 義手センサーからの信号が 胸の「手」に伝わればいいのです これは面白い

我々はまた 当初注目していた 肘から先を失った多数の患者の 義手についても考えました 筋肉の一部から神経を切り離して 神経支配を除き ほかの部分では神経をそのままにすると 上下運動を伝える神経と 手の開閉を伝える神経を 作れます 彼は初期の患者のクリスです 左側は8ヶ月使っている なじみの義手で 右は2ヶ月目の義手です 4~5倍のスピードで 動作テストをこなしています

順調に この仕事が好きなのは 研究仲間である患者さんが 同時に共同研究者だからです 本日その一人のアマンダ・キッツが 会場に来てくれました アマンダ・キッツです


アマンダ どうして腕を失ったのですか?

2006年に交通事故に遭いました 仕事から帰る途中 反対車線のトラックが突っ込んできて 車の前面が潰され その時 トラックの車軸に腕を巻き取られました

そうですか 腕を切断したあと回復したのですね 従来型の義手を使ったと思いますが 使い心地は如何でしたか?

少し難しかったです 上腕二頭筋と上腕三頭筋しか使えなくて 例えば何かを拾うという簡単な動作にも まずは肘を曲げ 筋を同時収縮させ モードを変える必要があります そして 上腕二頭筋を使って 手を閉じて 上腕三頭筋で手を開き また同時収縮させ 肘をまた動かすのです


少し遅いし とにかく大変なのです 集中力が要ります

オーケー そして9ヶ月後に 「特定領域への神経支配再確立」手術を 受けたと思いますが 神経支配が再確立するには さらに半年程かかったと思います そして改めて作った義手は どうでしたか?

良かったですよ 肘を使いながら 手も一緒に動かせるし それも思うだけで動かせます 同時収縮などあれこれ面倒はありません


少しだけ速いです ただすごく簡単で自然です

それを目指していたんです 20年間 私の目標は患者さんが 肘と手を直感的に そして同時に操作できる 義手の製作でした そして今 50人以上がこの手術を受けました 何十人もの米軍の 負傷兵も含まれます 手術の成功率は極めて高く 96%程成功しました 太い神経を細い筋に移植しているからです この手術が直感的な操作を可能にします 動作テストでは 速さと 簡易性の向上が示されました そして何より 患者さんが喜んでくれました

これが楽しかった しかしまだ改善したい 神経信号には多くの情報が含まれていますが もっと情報を引き出したい 指一本づつ 親指 手首を動かせます しかしもっと何かできないか? 実験を行いました 患者さんに無数の電極を取り付け 指先の動作から 何かへ腕を伸ばす 腕全体の動作まで20あまりの動作を 試してもらい データを集めました そしてパターン認識と呼ばれる 音声認識によく用いられる アルゴリズムを適用しました どうでしょう


ジェシーの胸を見れば 3つの動作に対応する 3つのパターンがわかります しかし電極に対し具体的な 動作の指示はできないので ニューブランズウィック大学と共同で アマンダがこれから披露する アルゴリズム制御を開発しました

まず肘を上下に動かすことができます 手首も回せるし しかもグルットとも回ります 手首も屈伸します 手の開閉もできます

ありがとう アマンダ これは実験段階の義手ですが ここから下は市販の部品でできています 残りの部品は世界中から借りてきました 3 kg程の重さです 私の腕を切り落としたら きっと そのくらいの重さです アマンダにはちょっと重いはずです しっかり取り付けていない義手なので 余計重く感じます 装着具でつけた腕ですからね

つまりメカトロニクス部分は 胸躍るようなものではありませんが 制御が素晴らしいのです 我々は小型のマイコンを開発しました アマンダの首の後ろでチカチカしながら 彼女がそれぞれの筋肉からの 信号パターンを使って 訓練に従って 動作しているのです アマンダ この義手を使い始めた時 慣れるまでどのくらいかかりました?

自分に適応させるまでに3-4時間といった そんなところです その間はコンピュータの側を 離れることはできず コンピューターが止まったら 外さなければいけません 今は背中の 小さな装置で同じことができ いつでもつけていられます 何かの理由で働かなくなっても もう一度訓練して 今度は1分程しかかかりません

つまり臨床的に使えるものを 開発できて 我々はとても興奮しています 実用に足るような そんな機器を 作るのが我々の望むことだったからです アマンダにはもっと進んだ 義手も使ってもらいました これはDEKA社の義手です ディーン・カーメンが 数年前TEDでデモを行ったものです とてもスムーズに 制御できています パターン認識の成果です 違った握り方のできる義手もあります 患者さんに義手の手を広げてもらい 「どんな握り方をしたいか」考えてもらうと そのモードになり これで 5~6種の握り方ができます アマンダ いくつの握り方ができますか?

4つです キーグリップ、チャックグリップ 強く握ること そして つまむことができます でも手を開いているのが一番好きですね 子ども相手の仕事では 手を叩いて歌うことが多いんです それがまたできるようになったのが嬉しいです



ありがとう メカトロニクスが進歩し 実地試験ができれば 何ができるか楽しみです ではこちらをご覧下さい


この患者はクローディアといい これは彼女が初めて 義手から感覚を得た場面です 義手の先端にセンサーがあり いくつかの違った表面をなでる毎に 違った感触を感じるのです 紙やすり 砂利 リボン 感触が 「神経支配を再確立した手」の皮膚に伝わります テーブルをなでると自分の指が 揺れ動くのを感じると言います これが皮膚感覚フィードバックの 可能性を示す実験となります

こちらはまた別の挑戦です ジェシーが泡粒玩具を握ると 強く握るほど胸についた黒い小さな機器が それに比例して彼の皮膚を強く押します ただ多くの電極を見ればわかる通り 皮膚の表面にぎっしりです 多くの電極を繋ぐ必要があり 電極に付属するモーターは とてもうるさいです 課題は多いですが我々は挑戦を続けています

将来は明るいです 今の技術にも 将来の技術にも希望が一杯です 例えばもっと 皮膚表面の問題を解決して 良い信号を得ることだとか 米粒のように非常に小さく 筋肉に入れることができ EMG信号を遠隔で取得できる カプセルを開発し 煩わしい配線などに 気をもまない様にしたいだとか 感覚のフィードバックを得るために 皮膚につけるものを減らすとか とにかく良い義手を作りたい この義手は平均的な男性用のサイズです 全人口の5/8の人間にとっては大き過ぎます そのため 私たちは強く 速い義手よりは ただ握り・開き 手首と肘だけは動かせる しかしサイズ的には 平均的な女性用のサイズより さらに小さい そんな義手の開発の優先を考えています その義手は最も小さく軽く 最も賢い義手です 小さな義手を開発すれば それを大きくするのは簡単です

これらが我々の目標です 今日はここに来てくださり有難うございます 最後に昨日私たちが体験した 義手の難しさについてお話します 時差ぼけしたアマンダが 義手を操作すると うまくいきませんでした システムが変な挙動をし ワイヤーが切れ 電圧変換機がスパークし ホテルの電気回路を全て使って 火災報知機が鳴りかけました その全てに私は対処できませんでしたが サイモン博士をはじめとする 優秀な研究チームのおかげで 昨日の問題を処理できました これが科学というものです 幸運にも 今日は問題なく動作しました



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