JP4060573B2

JP4060573B2 - Walking assist device

Info

Publication number: JP4060573B2
Application number: JP2001342408A
Authority: JP
Inventors: 宗平田; 工藤　　浩; 久加藤
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2001-11-07
Filing date: 2001-11-07
Publication date: 2008-03-12
Anticipated expiration: 2021-11-07
Also published as: JP2003135543A

Description

【０００１】
【発明の属する技術分野】
本発明は、アクチュエータを介して歩行者の脚体に補助力を付与することで、該歩行者の歩行を補助する装置に関する。
【０００２】
【従来の技術】
かかる歩行補助装置を使用することで、脚体等の筋力が低下した者でも階段や坂道の上り下り等の場合に苦を感じることなく歩行することができる。
【０００３】
【発明が解決しようとする課題】
しかし、補助力ばかりに依存して歩行し続けると、脚体の筋力がほとんど使われずに減退するため、かかる事態を回避すべく脚体に付与される補助力は適度に抑制されることが好ましい。また、補助力が付与されるタイミングによっては歩行者は意図せぬ不自然な姿勢での歩行を強要されることになり不快感を抱きかねない。
【０００４】
そこで、本発明は歩行者の筋力衰退等を防止しながら、歩行者に自然な姿勢での歩行を可能とする歩行補助装置を提供することを解決課題とする。
【０００５】
【課題を解決するための手段】
第１発明の歩行補助装置は、アクチュエータを介して歩行者の脚体に補助力を付与することで、該歩行者の歩行を補助する装置であって、歩行者の脚体が着床状態と離床状態とのいずれであるかを判定する脚体状態判定手段と、歩行者の大腿部の鉛直方向に対する傾斜角度を、股関節を含み、基本前額面に平行な平面を基準として前方を正、後方を負として定義される第１角度として測定する第１角度測定手段と、歩行者の歩行速度を測定する歩行速度測定手段と、装置の利用に伴う負荷を補償する補償力が脚体に付与されるようにアクチュエータを制御するとともに、該脚体状態判定手段により離床状態にあると判定された脚体について、第１角度測定手段により測定された第１角度が０°〜＋１０°の範囲で、且つ、該歩行速度手段により測定された歩行速度が２．０［ｋｍ／ｈ］以上の場合にのみ前記補償力に加えて補助力が該脚体に付与されるようにアクチュエータを制御する制御手段とを備えていることを特徴とする。
【０００６】
本願発明者の得た知見によれば、脚体が離床状態にあり、且つ、当該脚体の第１角度が０°〜＋１０°である場合、当該脚体の大腿部は慣性力により前方に振り上げられ、この振り上げには歩行者の筋力はほとんど用いられない。「第１角度」は鉛直方向に対する大腿部の傾斜角度であり、股関節を含み、基本前額面に平行な平面を基準として前方を正、後方を負として定義される。また、この場合、脚体に補助力が付与されても、当該脚体の姿勢は補助力が付与されない場合と比較して同等に維持される。
【０００７】
したがって、第１発明の歩行補助装置によれば、本来筋力がほとんど用いられない状態で脚体に補助力が付与されるので、補助力の付与が当該筋力の低下を招く事態を回避することができる。また、補助力が脚体に付与されてもこれが付与されない場合と比較して当該脚体の姿勢は同等なので、歩行者に不自然な姿勢での歩行を強いる事態を回避することができる。
【０００８】
第２発明の歩行補助装置は、第１発明の歩行補助装置において、歩行者の脚体の股関節角速度を測定する股関節角速度測定手段を備え、前記脚体状態判定手段は一の脚体について第１角度測定手段により測定された第１角度が正で該股関節角速度測定手段により測定された股関節角速度が正の所定角速度以上、且つ、他の脚体について第１角度測定手段により測定された第１角度が負で該股関節角速度測定手段により測定された股関節角速度が負の所定角速度以下の場合、該一の脚体が離床状態であり、該他の脚体が着床状態であると判定することを特徴とする。
【０００９】
第２発明の歩行補助装置によれば、後述のように歩行時の左右脚体の動きに関する定性的考察に基づき、脚体が着床・離床いずれの状態にあるかを判定することができる。
【００１０】
第３発明の歩行補助装置は、第１または第２発明の歩行補助装置において、歩行者の脛部の鉛直方向に対する傾斜角度を、膝関節を含み、基本前額面に平行な平面を基準として前方を正、後方を負として定義される第２角度として測定する第２角度測定手段と、歩行者の大腿部および脛部の長さを記憶保持する第１記憶手段とを備え、前記歩行速度測定手段は第１記憶手段に記憶保持されている大腿部および脛部の長さと、第１角度測定手段により測定された第１角度と、第２角度測定手段により測定された第２角度とに基づいて該歩行者の歩行速度を測定することを特徴とする。
【００１１】
第３発明の運動補助装置によれば、後述のように歩行者の脚体の長さ、関節における折れ曲り具合に関する初歩的な幾何学的考察に基づき、歩行者の歩行速度を測定することができる。
【００１２】
第４発明の歩行補助装置は、第１、第２または第３発明の歩行補助装置において、歩行者の歩行速度と、該歩行者の脚体に付与される補助力との相関関係を記憶保持する第２記憶手段と、前記歩行速度測定手段により測定された歩行速度と、第２記憶手段により記憶保持されている該相関関係とに基づいて前記アクチュエータを介して脚体に付与される補助力を決定する補助力決定手段とを備えていることを特徴とする。
【００１３】
第４発明の歩行補助装置によれば、後述のように予め構築された対応関係に基づいて適切な補助力を歩行者の脚体に付与することができる。
【００１４】
【発明の実施の形態】
本発明の歩行補助装置の実施形態について図面を用いて説明する。図１は本実施形態の歩行補助装置の構成説明図であり、図２は本実施形態の歩行補助装置の制御方法を示すフローチャートであり、図３は本実施形態の歩行補助装置における歩行速度の測定方法説明図であり、図４は本実施形態の歩行補助装置における脚体状態判定方法を示すフローチャートであり、図５は本実施形態の歩行補助装置による補助力の決定方法の説明図であり、図６は本実施形態の歩行補助装置による補助力の説明図であり、図７は本実施形態の歩行補助装置における第１角度θ₁−第２角度θ₂平面軌道図である。
【００１５】
図１に示す歩行補助装置は、歩行者の腹部に取り付けられて股関節回りの補助力を付与する左右の股関節アクチュエータ１１と、歩行者の膝部に取り付けられて膝関節回りの補助力を付与する左右の膝関節アクチュエータ１２と、アクチュエータ１１、１２の作動等を制御する制御ユニット（制御手段）２と、アクチュエータ１１、１２に電力を供給するＮｉ−ＭＨバッテリ等のバッテリ３とを備えている。制御ユニット２及びバッテリ３は歩行者の背中に装着されるバックパック４の中に格納されている。
【００１６】
股関節アクチュエータ１１は歩行者の腰部、大腿部に取り付けられる胴部サポータ５１及び大腿部サポータ５２を介して股関節回りの補助力を付与する。膝関節アクチュエータ１２は歩行者の大腿部、下腿部に取り付けられた大腿部サポータ５２及び下腿部サポータ５３を介して膝関節回りの補助力を付与する。
【００１７】
また、歩行補助装置は、歩行者の上体部に取り付けられ、上体部の鉛直方向に対する角速度を測定するジャイロセンサ６１と、前後方向の加速度を測定する前後加速度センサ６２とを備えている。さらに、歩行者の腰部に取り付けられ、腰部の鉛直方向に対する角速度を測定するジャイロセンサ６３と、前後方向、鉛直方向の加速度を測定する前後加速度センサ６４、上下加速度センサ６５とを備えている。また、歩行者の腰部にあって股関節角度、即ち、腰部に対する大腿部の角度φ₁を測定する左右の股関節角度センサ６６と、膝部にあって膝関節角度、即ち、大腿部に対する脛部の角度φ₂を測定する左右の膝関節角度センサ６７とを備えている。
【００１８】
制御ユニット２は、脚体状態判定手段２１と、第１角度測定手段２２１と、第２角度測定手段２２２と、股関節角速度測定手段２２３と、歩行速度測定手段２２４と、第１記憶手段２３１と、第２記憶手段２３２と、補助力決定手段２４とを備えている。
【００１９】
脚体状態判定手段２１は後述のように第１角度測定手段２２１により測定される第１角度θ₁等に基づき、左右の脚体がそれぞれ足裏が着床している着床状態であるか、足裏が離床している離床状態であるかを判定する。
【００２０】
第１角度測定手段２２１は腰部のジャイロセンサ６３からの出力に基づき測定された鉛直方向に対する腰部の傾斜角度φと、股関節角度センサ６６により測定された股関節角度φ₁とに基づいて第１角度（鉛直方向に対する大腿部の角度）θ₁を測定する。第２角度測定手段２２２は第１角度測定手段２２１により測定された第１角度θ₁と、膝関節角度センサ６７により測定された膝関節角度φ₂とに基づいて第２角度（鉛直方向に対する脛部の角度）θ₂を測定する。股関節角速度測定手段２２３は股関節角度センサ６６により測定される股関節角度φ₁を時間微分演算することで股関節角速度ω（＝ｄφ₁／ｄｔ）を測定する。歩行速度測定手段２２４は第１、第２角度測定手段２２１、２２２により測定される第１、第２角度θ₁、θ₂等に基づき、歩行者の歩行速度ｖを測定する。
【００２１】
第１記憶手段２３１はＲＯＭ、ＲＡＭ等により構成され、予め測定された歩行者の大腿部、下腿部の長さｌ₁、ｌ₂を記憶保持する。第２記憶手段２３２は予め実験結果により構築され、歩行速度ｖと脚体に付与される補助力Ｆとの対応関係（図６参照）を記憶保持する。
【００２２】
補助力決定手段２４は後述のように歩行速度測定手段２２により測定された歩行速度ｖ等に基づき、アクチュエータ１１、１２を介して股関節、膝関節回りに付与される補助力を決定する。
【００２３】
そして、制御ユニット２は補助力決定手段２４により決定された補助力が付与されるようにアクチュエータ１１、１２の駆動モータ（図示略）の電流値を制御する。
【００２４】
上記構成の歩行補助装置の機能について図２〜図７を用いて説明する。
【００２５】
まず、第１角度測定手段２２１、第２角度測定手段２２２、股関節角速度測定手段２２３、歩行速度測定手段２２４により左右の脚体について第１角度θ₁、第２角度θ₂、股関節角速度ω、歩行速度ｖが測定される（図２ｓ１）。
【００２６】
具体的には第１角度測定手段２２２は、腰部のジャイロセンサ６３により測定された鉛直方向に対する腰部の傾斜角度φと、股関節角度センサ６６により測定された股関節角度φ₁を用い、次式（１）に従って第１角度θ₁を測定する（図３参照）。なお、腰部の傾斜角φは基本前額面（身体を前後に二分する垂直面）を基準として腰部が前方に傾斜した場合は正、後方に傾斜した場合は負として定義される。また、股関節角度φ₁は股関節を含み、基本前額面を当該股関節の上方で腰部と同じく傾斜角φだけ傾斜させた平面に対し、大腿部が前方にある場合を正、後方にある場合を負として定義される。さらに、第１角度θ₁は股関節を含み、基本前額面に平行な平面を基準として前方を正、後方を負として定義される。
【００２７】
θ₁ ＝ φ₁− φ ‥（１）
【００２８】
また、第２角度測定手段２２２は、第１角度測定手段２２１により測定された第１角度θ₁と、膝関節角度センサ６７により測定された膝関節角度φ₂とを用い、次式（２）に従って第２角度θ₂を測定する（図３参照）。なお、膝関節角度φ₂は股関節を含み、基本前額面を当該股関節の下方で第１角度θ₁だけ傾斜させた平面に対し、脛部が前方にある場合を負、後方にある場合を正として定義される。また、第２角度θ₂は膝関節を含み、基本前額面に平行な平面を基準として前方を正、後方を負として定義される。
【００２９】
θ₂ ＝ θ₁− φ₂ ‥（２）
【００３０】
さらに、股関節角速度測定手段２２３は股関節角度センサ６６により測定された股関節角度φ₁を時間微分演算することで股関節角速度ω（＝ｄφ₁／ｄｔ）を測定する。なお、股関節角速度ωは大腿部が歩行方向に移動する場合を正、大腿部が歩行方向の逆方向に移動する場合を負として定義される。
【００３１】
また、歩行速度測定手段２２４は、歩行者の両脚体が着床状態（図３点線：時刻ｔ_i）になってから、一方の脚体を着床させたまま他方の脚体を離床させ、再度両脚体が着床状態（図３実線：時刻ｔ_i+1）になるまでの移動距離、所要時間に基づいて歩行速度ｖを測定する。腰部の上下加速度センサ６５の出力に基づいて測定される腰部の上方向の加速度が所定の閾値を越えたときをもって、両脚体が着床状態になった時刻とされる。また、当該時刻において第１、第２角度測定手段２２１、２２２により測定された第１、第２角度θ₁、θ₂と、第１記憶手段２３１により記憶保持されている歩行者の大腿部、脛部の長さｌ₁、ｌ₂とに基づき、歩行速度ｖを幾何学的考察に基づく次式（３）に従って測定する。
【００３２】
ｖ＝ｄ／（ｔ_i+1−ｔ_i）、
ｄ＝ｌ₁ｓｉｎθ₁（ｔ_i+1）＋ｌ₂ｓｉｎθ₂（ｔ_i+1）
−ｌ₁ｓｉｎθ₁（ｔ_i）−ｌ₂ｓｉｎθ₂（ｔ_i） ‥（３）
【００３３】
続いて、脚体状態判定手段２１が左右の脚体がそれぞれ離床状態にあるか着床状態にあるかを判定する（図２ｓ２）。具体的には図４に示すように右脚体について第１角度θ₁が０以上か否か、股関節角速度ωが正の所定角速度ｃ₊（＞０）以上か否か、左脚体について第１角度θ₁が負か否か、股関節角速度ωが負の所定角速度ｃ_-（＜０）以下か否かが判断される（ｓ２１ａ〜２４ａ）。そして、これら４つの条件が全て満たされているとき（ｓ２１ａ〜２４ａの全部でＹＥＳ）、右脚体が離床状態、左脚体が着床状態であると判定する（ｓ２５ａ）。
【００３４】
また、いずれかの条件が満たされていないとき（ｓ２１ａ〜２４ａのいずれかでＮＯ）、左脚体について第１角度θ₁が０以上か否か、股関節角速度ωが正の所定角速度ｃ₊（＞０）以上か否か、右脚体について第１角度θ₁が負か否か、股関節角速度ωが負の所定角速度ｃ_-（＜０）以下か否かが判断される（ｓ２１ｂ〜２４ｂ）。そして、これら４つの条件が全て満たされているとき（ｓ２１ｂ〜２４ｂの全てでＹＥＳ）、右脚体が着床状態、左脚体が離床状態であると判定する（ｓ２５ｂ）。なお、上記８つの条件の全てが満たされていないとき（ｓ２１ａ〜２４ａ、２１ｂ〜２４ｂの全てでＮＯ）、第１角度θ₁、第２角度θ₂等があらためて測定される（図４Ａ、図２ｓ１）。
【００３５】
脚体状態判定手段２１により離床状態であると判定された脚体については、続いて、制御ユニット２によって第１角度θ₁が０°以上１０°以下であるか否かが判断され（ｓ３）、さらに歩行速度ｖが所定速度ｖ₀＝２．０［ｋｍ／ｈ］以上か否かが判断される（ｓ４）。
【００３６】
第１角度θ₁が０°以上１０°以下、歩行速度ｖが所定速度ｖ₀＝２．０［ｋｍ／ｈ］以上であると判断された場合（ｓ３、ｓ４でＹＥＳ）、補助力決定手段２４が補助力を決定する（ｓ５）。具体的には補助力決定手段２４は第２記憶手段２３２により記憶保持されている歩行速度ｖと補助力との対応関係を読み取り、これと歩行速度測定手段２２４により測定された歩行速度ｖとに基づいて補助力を決定する。図５に歩行速度ｖと補助力との対応関係を示すが、歩行速度ｖが大きくなるほど補助力が大きく決定されることがわかる。
【００３７】
続いて、制御ユニット２が股関節アクチュエータ１１、必要に応じて適宜膝関節アクチュエータ１２の駆動モータ（図示略）の電流値を制御することで、補助力決定手段２４により決定された補助力が脚体に付与される（ｓ６）。
【００３８】
なお、制御ユニット２により股関節、膝関節アクチュエータ１１、１２を介してフリクション等、装置の使用に伴う負荷を定常的に補償する「補償力」が歩行者の脚体に付与される。従って「補償力」が脚体に付与されることで、本装置を装着した歩行者はあたかも本装置を装着していないときと同じ感覚で歩行することができる。また「補助力」は「補償力」に加えて付与され、これにより歩行者は本装置によりその歩行が補助されていることを実感することができる。
【００３９】
図６に歩行時間に対し、股関節に対して付与される補助力がどのように決定・付与されるかを示す。当該脚体が離床状態、第１角度θ₁が０°以上１０°以下、且つ、歩行速度ｖが所定速度ｖ₀＝２．０［ｋｍ／ｈ］以上である時間帯Ｒでは補償力（太線）に加え、補助力（細線）が付与されている。一方、時間帯Ｒを除く時間帯では補償力（太線）のみが付与されている。
【００４０】
そして、装置の作動が停止されない限り（ｓ７でＮＯ）、上述の処理（ｓ１〜ｓ６）が繰り返し実行される。
【００４１】
本装置によれば、脚体が離床状態で、第１角度θ₁が０°〜＋１０°である場合（図６の時間帯Ｒ）にのみ補償力（図６太線）に加えて補助力（図６細線）が付与される（図２ｓ５）。この場合、本願発明者の知見によれば、当該脚体の大腿部は慣性力により前方に振り上げられ、この振り上げには歩行者の筋力はほとんど用いられない。従って、本装置によれば、本来筋力がほとんど用いられない状態で脚体に補助力が付与されるので、補助力の付与が当該筋力の低下を招く事態を回避することができる。
【００４２】
ここで、図７に補償力のみが付与された場合の１歩行周期にわたるθ₁−θ₂軌跡（実線）と、離床状態の脚体の第１角度θ₁が０°〜＋１０°の範囲（一点鎖線で囲まれた範囲）内にあるときのみ補償力に加えて補助力が付与された場合の１歩行周期にわたるθ₁−θ₂軌跡（点線）とを示す。両軌跡を比較すると離床状態の脚体の第１角度θ₁が０°〜＋１０°の範囲ではほぼ同一の軌跡であり、全体としてもほぼ同形状である。これは、離床状態、且つ、第１角度θ₁が０°〜＋１０°の範囲にある脚体に補助力が付与されても当該脚体の姿勢は補助力が付与されない場合と比較して同等に維持され、歩行者に不自然な姿勢での歩行を強いる事態を回避することができることを意味する。
【００４３】
さらに、歩行速度ｖが２．０［ｋｍ／ｈ］）未満（図６の時間帯Ｒを除く時間帯）の場合は補助力は付与されない（図２ｓ４、ｓ５ｂ）。歩行速度ｖが２．０［ｋｍ／ｈ］未満の場合、歩行者が意図的にゆっくりと歩行していると推認されるよう設定されているので、補助力が脚体に付与されることで歩幅が大きくなる等、歩行者がその意に反する歩行を強要される事態を回避することができる。なお、２．０［ｋｍ／ｈ］の値は適宜変更設定されてもよい。
【００４４】
本実施形態では歩行速度ｖ、第１角度θ₁により補助力の付与条件が特定されたが（図２ｓ３、ｓ４参照）、他の実施形態としてこれらに加えて第２角度θ₂や上体部の傾斜角度、股関節角速度ω₁＝ｄφ₁／ｄｔ、膝関節角速度ω₂＝ｄφ₂／ｄｔにより当該条件が決定されてもよい。
【００４５】
本実施形態では上式（３）に従って歩行速度ｖが測定されたが、他の実施形態として股関節角速度ω₁＝ｄφ₁／ｄｔ、膝関節角速度ω₂＝ｄφ₂／ｄｔが股関節角度センサ６６、膝関節角度センサ６７の出力に基づいて測定された上で、歩行速度ｖが次式（４）に従って測定されてもよい。なお、前述のように股関節角速度ω₁は大腿部が歩行方向に移動する場合を正、大腿部が歩行方向の逆方向に移動する場合を負として定義される。また、膝関節角速度ω₂は膝関節が延びる方向を負、折れ曲る方向を正として定義される。
【００４６】
ｖ＝ｌ₁ω₁・ｃｏｓθ₁＋ｌ₂ω₂・ｃｏｓθ₂‥（４）
【図面の簡単な説明】
【図１】本実施形態の歩行補助装置の構成説明図
【図２】本実施形態の歩行補助装置の制御方法を示すフローチャート
【図３】本実施形態の歩行補助装置における歩行速度の測定方法説明図
【図４】本実施形態の歩行補助装置における脚体状態判定方法を示すフローチャート
【図５】本実施形態の歩行補助装置による補助力決定方法の説明図
【図６】本実施形態の歩行補助装置による補助力の説明図
【図７】本実施形態の歩行補助装置における第１角度θ₁−第２角度θ₂平面軌道図
【符号の説明】
１１‥股関節アクチュエータ、１２‥膝関節アクチュエータ、２‥制御ユニット、２１‥脚体状態判定手段、２２１‥第１角度測定手段、２２２‥第２角度測定手段、２２３‥股関節角速度測定手段、２２４‥歩行速度測定手段、２３１‥第１記憶手段、２３２‥第２記憶手段、２４‥補助力決定手段、６６‥股関節角度センサ、６７‥膝関節角度センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device that assists the walking of a pedestrian by applying an assisting force to the leg of the pedestrian via an actuator.
[0002]
[Prior art]
By using such a walking assist device, even those who have weak muscles such as legs can walk without feeling painful when going up and down stairs or hills.
[0003]
[Problems to be solved by the invention]
However, if walking continues depending only on the assisting force, the muscle strength of the leg is reduced without being used, so that the assisting force applied to the leg is preferably moderately suppressed to avoid such a situation. . Moreover, depending on the timing at which the assisting force is applied, the pedestrian may be forced to walk in an unnatural posture, which may cause discomfort.
[0004]
Then, this invention makes it a solution subject to provide the walking assistance apparatus which enables a walker to walk with a natural attitude | position, preventing a pedestrian's muscle strength decline.
[0005]
[Means for Solving the Problems]
The walking assist device of the first invention is a device that assists the walking of the pedestrian by applying an assisting force to the pedestrian's leg through an actuator, and the pedestrian's leg is in a landing state. The leg state determination means for determining whether the bed is in a state of bed leaving, the inclination angle of the pedestrian's thigh with respect to the vertical direction , including the hip joint, the front is positive with reference to a plane parallel to the basic frontal plane, A first angle measuring means that measures the rear as a first angle defined as negative, a walking speed measuring means that measures the walking speed of the pedestrian, and a compensation force that compensates for the load associated with the use of the device is applied to the leg. The first angle measured by the first angle measuring means is in the range of 0 ° to + 10 ° with respect to the leg that is determined to be out of bed by the leg state determining means. And by the walking speed means Control means for controlling the actuator so that an auxiliary force is applied to the leg body in addition to the compensation force only when the measured walking speed is 2.0 [km / h] or more. Features.
[0006]
According to the knowledge obtained by the present inventor, when the leg is in a bed leaving state and the first angle of the leg is 0 ° to + 10 °, the thigh of the leg is moved forward by inertial force. The pedestrian's muscle strength is hardly used for this swing-up. The “first angle” is an inclination angle of the thigh with respect to the vertical direction, and is defined as positive on the front side and negative on the back side with respect to a plane including the hip joint and parallel to the basic frontal plane . Further, in this case, even if the assisting force is applied to the leg, the posture of the leg is maintained equivalent to the case where the assisting force is not applied.
[0007]
Therefore, according to the walking assist device of the first invention , the assisting force is applied to the leg in a state where essentially no muscle force is used, and therefore it is possible to avoid a situation where the application of the assisting force causes a decrease in the muscle strength. it can. Moreover, since the posture of the leg body is the same as the case where the assist force is applied to the leg body as compared with the case where the assist force is not applied, it is possible to avoid a situation in which the pedestrian is forced to walk in an unnatural posture.
[0008]
A walking assist device according to a second aspect of the present invention is the walking assist device according to the first aspect , further comprising hip joint angular velocity measuring means for measuring a hip joint angular velocity of a pedestrian's leg, wherein the leg state determining means is the first for one leg. The first angle measured by the angle measuring means is positive, the hip joint angular velocity measured by the hip joint angular velocity measuring means is not less than a predetermined positive angular velocity, and the first angle measured by the first angle measuring means for the other legs. If the hip joint angular velocity measured by the hip joint angular velocity measuring means is equal to or less than the negative predetermined angular velocity, the one leg is determined to be out of bed and the other leg is determined to be in the landing state. Features.
[0009]
According to the walking assist device of the second invention, it is possible to determine whether the leg is in the landing state or the leaving state based on the qualitative consideration regarding the movement of the left and right legs during walking as described later.
[0010]
The walking assist device of the third invention is the walking assist device of the first or second invention, wherein the inclination angle of the pedestrian's shin portion with respect to the vertical direction is forward with reference to a plane including the knee joint and parallel to the basic frontal plane. A second angle measuring means that measures the second angle defined as positive and backward as a negative angle, and a first storage means that stores and holds the lengths of the thighs and shins of the pedestrian. The measuring means includes the lengths of the thighs and shins stored and held in the first storage means, the first angle measured by the first angle measuring means, and the second angle measured by the second angle measuring means. The walking speed of the pedestrian is measured based on the above.
[0011]
According to the exercise assisting device of the third invention , the walking speed of the pedestrian can be measured based on elementary geometrical considerations regarding the length of the pedestrian's leg and the bending state of the joint as described later. it can.
[0012]
The walking assist device according to a fourth aspect of the present invention is the walking assist device according to the first, second or third aspect of the present invention, which stores and holds the correlation between the walking speed of the pedestrian and the assisting force applied to the leg of the pedestrian. Assisting force applied to the leg via the actuator based on the second storage means, the walking speed measured by the walking speed measuring means, and the correlation stored and held by the second storage means And an auxiliary force determining means for determining.
[0013]
According to the walking assist device of the fourth aspect of the present invention, an appropriate assisting force can be applied to the pedestrian's leg based on the correspondence established in advance as described below.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a walking assistance device of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of the configuration of the walking assist device of the present embodiment, FIG. 2 is a flowchart showing a control method of the walking assist device of the present embodiment, and FIG. 3 shows the walking speed of the walking assist device of the present embodiment. FIG. 4 is a flowchart illustrating a method for determining leg state in the walking assist device of the present embodiment, and FIG. 5 is an explanatory diagram of a method for determining assisting force by the walking assist device of the present embodiment. FIG. 6 is an explanatory diagram of the assisting force by the walking assistance device of the present embodiment, and FIG. 7 is a plan view of the first angle θ ₁ -second angle θ ₂ in the walking assistance device of the present embodiment.
[0015]
The walking assist device shown in FIG. 1 is attached to a pedestrian's abdomen and applies left and right hip joint actuators 11 that apply auxiliary force around the hip joint, and attached to the pedestrian's knee and applies auxiliary force around the knee joint. It includes a left and right knee joint actuator 12, a control unit (control means) 2 that controls the operation of the actuators 11, 12, and a battery 3 such as a Ni-MH battery that supplies power to the actuators 11, 12. The control unit 2 and the battery 3 are stored in a backpack 4 that is worn on the back of a pedestrian.
[0016]
The hip joint actuator 11 provides an assisting force around the hip joint via the waist supporter 51 and the thigh supporter 52 attached to the waist and thighs of the pedestrian. The knee joint actuator 12 applies assisting force around the knee joint via a thigh supporter 52 and a lower leg supporter 53 attached to the thigh and lower leg of the pedestrian.
[0017]
The walking assist device includes a gyro sensor 61 that is attached to the body part of the pedestrian and that measures an angular velocity of the body part with respect to the vertical direction, and a longitudinal acceleration sensor 62 that measures acceleration in the longitudinal direction. Furthermore, it is provided with a gyro sensor 63 that is attached to the waist of the pedestrian and measures the angular velocity of the waist with respect to the vertical direction, a longitudinal acceleration sensor 64 that measures acceleration in the longitudinal direction and the vertical direction, and a vertical acceleration sensor 65. Further, the hip joint angle In the waist of the pedestrian, i.e., left and right hip joint angle sensor 66 for measuring the angle phi ₁ of the thigh with respect to the waist, the knee joint angle In the knee, i.e., shin against the thigh the Department of angle phi ₂ and a right and left knee joint angle sensor 67 that measures.
[0018]
The control unit 2 includes a leg state determination unit 21, a first angle measurement unit 221, a second angle measurement unit 222, a hip joint angular velocity measurement unit 223, a walking speed measurement unit 224, a first storage unit 231, Second storage means 232 and auxiliary force determination means 24 are provided.
[0019]
Whether the leg state determining means 21 is in a landing state where the left and right legs are respectively in contact with the soles based on the first angle θ ₁ measured by the first angle measuring means 221 as described later. Then, it is determined whether the floor is in the state of getting out of bed.
[0020]
The first angle measuring means 221 uses the first angle (based on the inclination angle φ of the waist with respect to the vertical direction measured based on the output from the gyro sensor 63 of the waist and the hip joint angle φ ₁ measured by the hip joint angle sensor 66). Measure the angle of the thigh (vertical direction) θ ₁ . The second angle measuring means 222 is based on the first angle θ ₁ measured by the first angle measuring means 221 and the knee joint angle φ ₂ measured by the knee joint angle sensor 67. Part angle) θ ₂ is measured. The hip joint angular velocity measuring means 223 measures the hip joint angular velocity ω (= dφ ₁ / dt) by time-differentiating the hip joint angle φ ₁ measured by the hip joint angle sensor 66. The walking speed measuring unit 224 measures the walking speed v of the pedestrian based on the first and second angles θ ₁ and θ ₂ measured by the first and second angle measuring units 221 and 222.
[0021]
The first storage means 231 is composed of a ROM, a RAM, and the like, and stores and holds the lengths l ₁ and l ₂ of the pedestrian's thigh and crus measured in advance. The second storage means 232 is constructed in advance by experimental results, and stores and holds the correspondence (see FIG. 6) between the walking speed v and the auxiliary force F applied to the legs.
[0022]
The assisting force determining means 24 determines the assisting force applied to the hip joint and the knee joint via the actuators 11 and 12 based on the walking speed v measured by the walking speed measuring means 22 as described later.
[0023]
And the control unit 2 controls the electric current value of the drive motor (not shown) of the actuators 11 and 12 so that the auxiliary force determined by the auxiliary force determining means 24 is applied.
[0024]
The function of the walking assistance device having the above configuration will be described with reference to FIGS.
[0025]
First, the first angle θ ₁ , the second angle θ ₂ , the hip joint angular velocity ω, the walking with respect to the left and right legs by the first angle measuring means 221, the second angle measuring means 222, the hip joint angular velocity measuring means 223, and the walking speed measuring means 224. The velocity v is measured (Fig. 2s1).
[0026]
Specifically, the first angle measurement means 222 uses the waist inclination angle φ with respect to the vertical direction measured by the waist gyro sensor 63 and the hip joint angle φ ₁ measured by the hip joint angle sensor 66, and the following equation (1 ) To measure the first angle θ ₁ (see FIG. 3). In addition, the inclination | tilt angle (phi) of a waist | hip | lumbar part is defined as positive when the waist | hip | lumbar part inclines forward on the basis of the basic frontal plane (vertical surface which bisects the body back and forth), and negative when it inclines back. Further, the hip joint angle φ ₁ includes the hip joint, and the case where the thigh is in the front and the rear in the plane where the basic frontal plane is inclined by the tilt angle φ above the hip joint in the same manner as the waist. Defined as negative. Further, the first angle θ ₁ includes the hip joint, and is defined as positive on the front and negative on the back with respect to a plane parallel to the basic frontal plane.
[0027]
θ ₁ = φ ₁ − φ (1)
[0028]
The second angle measuring means 222 uses the first angle θ ₁ measured by the first angle measuring means 221 and the knee joint angle φ ₂ measured by the knee joint angle sensor 67, and the following equation (2) Then, the second angle θ ₂ is measured (see FIG. 3). Note that the knee joint angle φ ₂ includes the hip joint, and is negative when the shin is forward and negative when it is behind the plane with the basic frontal plane inclined by the first angle θ ₁ below the hip joint. Is defined as The second angle θ ₂ includes the knee joint, and is defined as positive on the front and negative on the back with respect to a plane parallel to the basic frontal plane.
[0029]
θ ₂ = θ ₁ − φ ₂ (2)
[0030]
Further, the hip joint angular velocity measuring means 223 measures the hip joint angular velocity ω (= dφ ₁ / dt) by time-differentiating the hip joint angle φ ₁ measured by the hip joint angle sensor 66. The hip joint angular velocity ω is defined as positive when the thigh moves in the walking direction and negative when the thigh moves in the opposite direction of the walking direction.
[0031]
Further, the walking speed measuring means 224 causes the other leg to leave the floor while one leg remains on the ground after both legs of the pedestrian are in the landing state (dotted line in FIG. 3: time t _i ). The walking speed v is measured based on the moving distance and the required time until both legs again reach the landing state (solid line in FIG. 3: time t _{i + 1} ). The time when the upper body acceleration measured on the basis of the output of the waist vertical acceleration sensor 65 exceeds a predetermined threshold is the time when both legs are in the landing state. Further, the first and second angles θ ₁ and θ ₂ measured by the first and second angle measuring means 221 and 222 at the time, and the thigh of the pedestrian stored and held by the first storage means 231. Based on the lengths l ₁ and l _{2 of} the shin part, the walking speed v is measured according to the following equation (3) based on geometric considerations.
[0032]
v = d / (t _{i + 1} −t _i ),
d = l ₁ sin θ ₁ (t _{i + 1} ) + l ₂ sin θ ₂ (t _{i + 1} )
−l ₁ sin θ ₁ (t _i ) −l ₂ sin θ ₂ (t _i ) (3)
[0033]
Subsequently, the leg state determination means 21 determines whether the left and right legs are in a bed leaving state or a landing state (FIG. 2 s2). Specifically, as shown in FIG. 4, whether or not the first angle θ ₁ is greater than or equal to 0 for the right leg, whether or not the hip joint angular velocity ω is greater than or equal to a predetermined positive angular velocity c ₊ (> 0), It is determined whether or not one angle θ ₁ is negative and whether or not the hip joint angular velocity ω is equal to or less than a predetermined negative angular velocity c ₋ (<0) (s21a to 24a). When all of these four conditions are satisfied (YES in all of s21a to 24a), it is determined that the right leg is in the leaving state and the left leg is in the landing state (s25a).
[0034]
Further, when any of the conditions is not satisfied (NO in any of s21a to 24a), the first angle θ ₁ is 0 or more for the left leg, and the hip joint angular velocity ω is a positive predetermined angular velocity c ₊ ( > 0) or more, whether or not the first leg θ ₁ is negative for the right leg, and whether or not the hip joint angular velocity ω is equal to or less than a predetermined negative angular velocity c ₋ (<0) (s21b to 24b). . When all of these four conditions are satisfied (YES in all of s21b to 24b), it is determined that the right leg is in the landing state and the left leg is in the leaving state (s25b). When all of the above eight conditions are not satisfied (NO in all of s21a to 24a and 21b to 24b), the first angle θ ₁ , the second angle θ _2, etc. are measured again (FIG. 4A, FIG. 2s1).
[0035]
For the leg that has been determined to be out of bed by the leg state determining means 21, it is subsequently determined by the control unit 2 whether or not the first angle θ ₁ is between 0 ° and 10 ° (s3). Further, it is determined whether or not the walking speed v is equal to or higher than the predetermined speed v ₀ = 2.0 [km / h] (s4).
[0036]
When it is determined that the first angle θ ₁ is not less than 0 ° and not more than 10 ° and the walking speed v is not less than the predetermined speed v ₀ = 2.0 [km / h] (YES in s3 and s4), the auxiliary force determining means 24 determines the assisting force (s5). Specifically, the auxiliary force determining means 24 reads the correspondence relationship between the walking speed v stored and held in the second storage means 232 and the auxiliary force, and converts this into the walking speed v measured by the walking speed measuring means 224. Auxiliary power is determined based on this. FIG. 5 shows a correspondence relationship between the walking speed v and the assisting force, and it can be seen that the assisting force is determined to be larger as the walking speed v increases.
[0037]
Subsequently, the control unit 2 controls the current value of the hip joint actuator 11 and, if necessary, the drive motor (not shown) of the knee joint actuator 12, so that the auxiliary force determined by the auxiliary force determining means 24 is the leg. (S6).
[0038]
The control unit 2 applies a “compensation force” to the pedestrian's legs through the hip joint and knee joint actuators 11 and 12 to steadily compensate for a load associated with the use of the apparatus, such as friction. Therefore, by providing “compensation power” to the leg, a pedestrian wearing this apparatus can walk with the same feeling as when not wearing this apparatus. In addition to the “compensation force”, the “assisting force” is given, so that the pedestrian can feel that the walking is assisted by this apparatus.
[0039]
FIG. 6 shows how the auxiliary force applied to the hip joint is determined and applied to the walking time. Compensation force (thick line) in the time zone R in which the leg is in a bed leaving state, the first angle θ ₁ is 0 ° or more and 10 ° or less, and the walking speed v is a predetermined speed v ₀ = 2.0 [km / h] or more. ) And auxiliary power (thin lines). On the other hand, only the compensation power (thick line) is applied in the time zone excluding the time zone R.
[0040]
Then, as long as the operation of the apparatus is not stopped (NO in s7), the above processing (s1 to s6) is repeatedly executed.
[0041]
According to the present apparatus, in addition to the compensation force (thick line in FIG. 6), the auxiliary force (the thick line in FIG. 6) is applied only when the leg is in a bed leaving state and the first angle θ ₁ is 0 ° to + 10 ° (time zone R in FIG. 6). A thin line in FIG. 6 is given (FIG. 2 s5). In this case, according to the knowledge of the present inventor, the thigh of the leg is swung forward by the inertial force, and the muscular strength of the pedestrian is hardly used for this swinging up. Therefore, according to the present apparatus, since the assisting force is applied to the leg in a state where essentially no muscle force is used, it is possible to avoid a situation in which the application of the assisting force causes a decrease in the muscle strength.
[0042]
Here, the θ ₁ -θ ₂ trajectory (solid line) over one walking cycle when only the compensation force is given in FIG. 7 and the first angle θ ₁ of the leg in the state of getting out of bed are in the range of 0 ° to + 10 ° ( A θ ₁ -θ ₂ trajectory (dotted line) over one walking cycle in the case where auxiliary force is applied in addition to compensation force only when it is within a range surrounded by a one-dot chain line). Comparing both trajectories, the first legs θ ₁ of the legs in the state of getting out of bed are substantially the same in the range of 0 ° to + 10 °, and the overall shape is substantially the same. This is equivalent to the case where the assisting force is applied to the leg in the state of getting out of bed and the first angle θ ₁ is in the range of 0 ° to + 10 ° compared to the case where the assisting force is not applied. This means that it is possible to avoid a situation in which a pedestrian is forced to walk in an unnatural posture.
[0043]
Further, when the walking speed v is less than 2.0 [km / h] (time zone excluding the time zone R in FIG. 6), no assisting force is applied (FIG. 2 s4, s5b). When the walking speed v is less than 2.0 [km / h], it is set so that the pedestrian is intentionally walking slowly, so that auxiliary power is applied to the leg. It is possible to avoid a situation in which a pedestrian is forced to walk contrary to his intention, such as an increase in stride. Note that the value of 2.0 [km / h] may be changed and set as appropriate.
[0044]
In this embodiment, the condition for applying the assisting force is specified by the walking speed v and the first angle θ ₁ (see s3 and s4 in FIG. 2), but in addition to these, the second angle θ ₂ and the body part are added. These conditions may be determined by the inclination angle, hip joint angular velocity ω ₁ = dφ ₁ / dt, and knee joint angular velocity ω ₂ = dφ ₂ / dt.
[0045]
In this embodiment, the walking speed v is measured according to the above equation (3). As another embodiment, the hip joint angular velocity ω ₁ = dφ ₁ / dt and the knee joint angular velocity ω ₂ = dφ ₂ / dt are the hip joint angle sensor 66, The walking speed v may be measured according to the following equation (4) after being measured based on the output of the knee joint angle sensor 67. As described above, the hip joint angular velocity ω ₁ is defined as positive when the thigh moves in the walking direction and negative when the thigh moves in the direction opposite to the walking direction. The knee joint angular velocity ω ₂ is defined as a direction in which the knee joint extends is negative and a direction in which the knee joint is bent is positive.
[0046]
v = l ₁ ω ₁ · cos θ ₁ + l ₂ ω ₂ · cos θ ₂ (4)
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the configuration of a walking assistance device according to the present embodiment. FIG. 2 is a flowchart illustrating a control method for the walking assistance device according to the present embodiment. FIG. 4 is a flowchart showing a leg state determination method in the walking assist device of the present embodiment. FIG. 5 is an explanatory diagram of an assisting force determination method by the walking assist device of the present embodiment. FIG. 7 is a diagram illustrating the first angle θ ₁ -second angle θ ₂ plane trajectory in the walking assist device of the present embodiment.
DESCRIPTION OF SYMBOLS 11 ... Hip joint actuator, 12 ... Knee joint actuator, 2 ... Control unit, 21 ... Leg state determination means, 221 ... First angle measurement means, 222 ... Second angle measurement means, 223 ... Hip joint angular velocity measurement means, 224 ... Walking Speed measuring means, 231 ... first storage means, 232 ... second storage means, 24 ... auxiliary force determining means, 66 ... hip joint angle sensor, 67 ... knee joint angle sensor

Claims

A device for assisting the walking of the pedestrian by applying an assisting force to the leg of the pedestrian via an actuator,
Leg state determination means for determining whether the pedestrian's leg is in a landing state or a leaving state; and
First angle measuring means for measuring the inclination angle of the pedestrian's thigh with respect to the vertical direction as a first angle defined as positive forward and negative negative with respect to a plane including the hip joint and parallel to the basic frontal plane. When,
Walking speed measuring means for measuring the walking speed of the pedestrian,
The actuator is controlled so that a compensation force for compensating for a load associated with the use of the apparatus is applied to the leg, and the first angle measuring means for the leg determined to be in the bed leaving state by the leg state determining means. In addition to the compensation force only when the first angle measured by the step is in the range of 0 ° to + 10 ° and the walking speed measured by the walking speed means is 2.0 [km / h] or more. A walking assist device comprising: a control unit that controls the actuator so that force is applied to the leg.

The walking assist device according to claim 1,
A hip joint angular velocity measuring means for measuring a hip joint angular velocity of a pedestrian's leg;
The leg state determining means is such that the first angle measured by the first angle measuring means for one leg is positive and the hip joint angular velocity measured by the hip joint angular velocity measuring means is equal to or greater than a positive predetermined angular velocity and the other leg. When the first angle measured by the first angle measuring means is negative and the hip joint angular velocity measured by the hip joint angular velocity measuring means is equal to or less than the negative predetermined angular velocity, the one leg is in the state of getting out of bed, It is determined that the leg of the person is in a landing state.

The walking assist device according to claim 1 or 2,
Second angle measuring means for measuring an inclination angle with respect to the vertical direction of the shin part of the pedestrian as a second angle defined as positive forward and negative negative with respect to a plane including the knee joint and parallel to the basic frontal plane. When,
First storage means for storing and holding the length of the thigh and shin of the pedestrian,
The walking speed measuring means stores the length of the thigh and shin stored in the first storage means, the first angle measured by the first angle measuring means, and the first angle measured by the second angle measuring means. A walking assist device that measures the walking speed of the pedestrian based on two angles.

The walking assist device according to claim 1, 2, or 3,
Second storage means for storing and holding a correlation between the walking speed of the pedestrian and the assisting force applied to the leg of the pedestrian, walking speed measured by the walking speed measuring means, and second storage means A walking assisting device comprising: an assisting force determining means for determining an assisting force applied to the leg via the actuator based on the correlation stored and held by the actuator.