JP4660718B2

JP4660718B2 - Position detection method and position detection apparatus

Info

Publication number: JP4660718B2
Application number: JP2001117694A
Authority: JP
Inventors: 博文玉井
Original assignee: Muscle Corp
Current assignee: Muscle Corp
Priority date: 2001-04-17
Filing date: 2001-04-17
Publication date: 2011-03-30
Anticipated expiration: 2021-04-17
Also published as: JP2002310610A

Description

【０００１】
【発明の属する技術分野】
本発明は、位置検出方法および位置検出装置に関する。さらに詳しくは、モータのロータ、回転軸および出力軸などの可動部、ならびにこれらモータの可動部により駆動される被駆動部を含むモータ機構の可動部の絶対位置を検出するための位置検出方法および位置検出装置に関する。
【０００２】
【従来の技術】
従来より、サーボモータなどの制御モータの回転位置を検出する位置センサとして、ロータリ・エンコーダ、レゾルバおよびパルスジェネレータなどが広く用いられている。
【０００３】
ロータリ・エンコーダは、インクリメンタル式とアブソリュート式に分類される。前者のインクリメンタル式は、基準位置（原点）を検出し、この基準位置からのロータの回転量を計測することによって可動部の絶対位置を検出する方式であるため、センサの始動時直後から基準位置が検出されるまでの間は絶対位置が不明であるという欠点がある。一方、後者のアブソリュート式は、常に絶対位置を検出することは可能であるが、要求される分解能に応じた検出点数（通常８〜１２チャンネル）を用いる必要があり、機構が複雑化しコストアップの要因になるという問題がある。
【０００４】
レゾルバは、通常モータの１回転が１周期に相当するアナログの正弦波状信号を生成し絶対位置を検出する構成であるため、検出精度が生成される正弦波状信号の精度に大きく依存し、したがって装置の製作精度を高精度にしないと精確な絶対位置検出を行うことができないという問題がある。
【０００５】
パルスジェネレータによる方式は、インクリメンタル式エンコーダと同様の欠点を有している。
【０００６】
このように、従来行われている各種位置検出方法や方式には、それぞれ長所および短所がある。
【０００７】
ここで、理想とされる位置検出方法や方式は、アブソリュート式エンコーダのような高精度性を有し、かつパルスジェネレータのような低コスト性を併せもつ位置検出方法や方式であるといえる。
【０００８】
【発明が解決しようとする課題】
本発明はかかる従来技術の課題に鑑みなされたものであって、モータ機構の絶対位置を常時高精度にかつ低コストな機構で検出することができる位置検出方法および位置検出装置を提供することを目的としている。
【０００９】
【課題を解決するための手段】
本発明の位置検出方法は、モータ機構の可動部の位置を表す、２種類の周波数の各正弦波電圧信号および各余弦波電圧信号を発生する信号発生手段を設け、可動部の運動の１周期において前記信号発生手段が発生する、各正弦波電圧信号および各余弦波電圧信号の波の数が、１または１を超えない範囲で相違するように前記２種類の周波数を設定し、前記２種類の周波数の各正弦波電圧信号および各余弦波電圧信号に基づいて、前記可動部の絶対位置を検出する位置検出方法において、前記２種類の周波数の各正弦波電圧信号および各余弦波電圧信号から可動部の運動の１周期以上の所定周期を有する正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて絶対位置の概略値を検出し、ついでその検出時における前記正弦波電圧信号または余弦波電圧信号の電圧値を満足する修正絶対位置候補を選出し、しかる後前記修正絶対位置候補の中から前記概略値に一番近い候補を精確な絶対位置とすることを特徴とする。
【００１１】
本発明の位置検出装置は、モータ機構の可動部の絶対位置を検出する位置検出装置であって、信号生成手段と、演算処理手段とを備え、前記信号生成手段が、可動部の運動の１周期における波の数が１または１を超えない範囲で相違する、２種類の周波数の各正弦波電圧信号および各余弦波電圧信号を生成し、前記演算処理手段が、前記２種類の周波数の各正弦波電圧信号および各余弦波電圧信号から可動部の運動の１周期以上の所定周期を有する正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて絶対位置の概略値を検出し、ついでその検出時における前記正弦波電圧信号または余弦波電圧信号の電圧値を満足する修正絶対位置候補を選出し、しかる後前記修正絶対位置候補の中から前記概略値に一番近い候補を精確な絶対位置とすることを特徴とする。
【００１３】
また、本発明の位置検出装置においては、例えば、信号生成手段が、可動部に装着された歯数が互いに１異なる各歯車と、この各歯車の歯にそれぞれ対向配置された各磁気ユニットとを含み、前記各磁気ユニットが、対応する歯車の歯に磁極が対向させて配設された磁石と、前記磁石と前記対応する歯車の歯との間に、同歯車の歯のピッチに対して１／４ピッチの間隔を設けて配設された２個の磁気抵抗素子とを有し、前記各歯車の歯形が、電圧信号として正弦波状の電圧波形が出力されるように形成され、前記磁気抵抗素子が、前記各歯車が回転することにより生ずる透過磁束の変化に応じて、位相が１／４波長ずれた２つの正弦波状の電圧信号を正弦波信号および余弦波信号として得るように回路構成され、前記演算処理手段が、各磁気ユニットからの２種類の周波数の各正弦波電圧信号および各余弦波電圧信号を用いて、可動部の運動の周期と同一周期の正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて可動部の絶対位置を検出するものとされる。この場合、各歯車が、モータの回転軸に装着され、またモータ機構が、ロータの回転を減速する減速機を備え、各歯車が、前記減速機の出力軸に装着されてもよく、さらに前記モータ機構が、回転軸または出力軸により駆動される被駆動部を含み、各歯車が前記被駆動部に装着されてもよい。
【００１４】
さらに、本発明の位置検出装置においては、例えば、被駆動部がモータの回転により所定範囲で直線的に駆動される直動部材とされ、信号生成手段が、前記直動部材に前記所定範囲に亘って歯数が互いに１異なるように設けられた各位置検出用ラックと、この各ラックの歯にそれぞれ対向配置された各磁気ユニットとを含み、前記各磁気ユニットが、対応するラックの歯に磁極が対向させて配設された磁石と、前記磁石と前記対応するラックの歯との間に、同ラックの歯のピッチに対して１／４ピッチの間隔を設けて配設された２個の磁気抵抗素子とを有し、前記各ラックの歯形が、電圧信号として正弦波状の電圧波形が出力されるように形成され、前記磁気抵抗素子が、前記各ラックが移動することにより生ずる透過磁束の変化に応じて、位相が１／４波長ずれた２つの正弦波状の電圧信号を正弦波信号および余弦波信号として得るように回路構成され、前記演算処理手段が、各磁気ユニットからの２種類の各正弦波電圧信号および各余弦波電圧信号を用いて、前記直動部材の運動の周期と同一周期の正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて前記直動部材の概略の絶対位置を検出するようにされてもよい。
【００１５】
さらに、本発明の位置検出装置においては、例えば、信号生成手段が、直動部材に設けられた伸縮自在なラックと、前記直動部材を移動方向に伸張させる伸張手段と、前記ラックの歯に対向配置された磁気ユニットとを含み、前記伸張手段が、前記直動部材を前記ラックの伸縮範囲内において同ラックの歯数が１または１を超えない所定数減少するよう前記直動部材を瞬時に伸張するものとされ、前記磁気ユニットが、磁極がラックの歯に対向させて配設された磁石と、前記磁石と前記ラックの歯との間に、前記伸張手段による伸張前と伸張時の各状態における前記ラックの歯のピッチに対して１／４ピッチの間隔を設けて配置されるよう設けられる２個の磁気抵抗素子とを有し、前記ラックの歯形が、電圧信号として正弦波状の電圧波形が出力されるように形成され、前記磁気抵抗素子が、前記ラックが移動することにより生ずる透過磁束の変化に応じて、位相が１／４波長ずれた２つの正弦波状の電圧信号を正弦波信号および余弦波信号として得るように回路構成され、演算処理手段が、前記伸張手段による前記直動部材の伸張前と伸張時の各状態で磁気ユニットから生成する２種類の周波数の各正弦波電圧信号および各余弦波電圧信号を用いて、前記直動部材の運動の周期以上の所定周期の正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて前記直動部材の絶対位置を概略的に演算するようにされてもよい。この場合、伸張手段による直動部材の伸び量を検出する伸び量検出手段を備え、該伸び量検出手段の検出結果に応じてラックの歯が減少する所定数を補正するようにされるのが好ましい。
【００１６】
さらに、本発明の位置検出装置においては、例えば、前記信号生成手段が、前記可動部に装着された歯車と、この歯車の歯形成部分を周方向に伸張する伸張手段と、前記歯車の歯に対向配置された磁気ユニットとを含み、前記歯車が、歯形成部分に周方向に対して斜めに切れ込みを有し、前記伸張手段が、前記歯車の歯数が１を超えない所定数減少するよう前記歯車の歯形成部分を周方向に瞬時に伸張するものとされ、前記磁気ユニットが、磁極が前記歯車の歯に対向させて配設された磁石と、前記磁石と前記歯車の歯との間に、前記伸張手段による伸張前と伸張後の各状態における前記歯車の歯の各ピッチに対して１／４ピッチの間隔を設けて配置されるように、前記伸張手段による前記歯車の伸張と連動するよう設けられる２個の磁気抵抗素子とを有し、前記磁気抵抗素子が、前記歯車が回転することにより生ずる透過磁束の変化に応じて、位相が１／４波長ずれた２つの正弦波状の電圧信号を前記正弦波信号および前記余弦波信号として得るように回路構成され、前記概略位置演算手段が、前記伸張手段による前記歯車の伸張前と伸張後の各状態における磁気ユニットからの２種類の周波数の各正弦波電圧信号および各余弦波電圧信号を用いて、前記可動部の運動の周期以上の所定周期の正弦波電圧信号および余弦波電圧信号を生成し、この正弦波電圧信号および余弦波電圧信号に基づいて前記可動部の絶対位置を概略的に演算するようにされてもよい。この場合、伸張手段による歯車の伸び量を検出する伸び量検出手段を備え、該伸び量検出手段の検出結果に応じて前記歯車の歯が減少する所定数を補正するようにされるのが好ましい。
【００１７】
【作用】
本発明は前記の如く構成されているので、２種類の周波数の各正弦波信号および各余弦波信号に基づいてモータ機構の可動部の絶対位置を常時精確に検出することができる。
【００１８】
【発明の実施の形態】
以下、添付図面を参照しながら本発明を実施形態に基づいて説明するが、本発明はかかる実施形態のみに限定されるものではない。
【００１９】
図１に本発明の一実施形態に係る位置検出方法が適用される位置検出装置の概略構成を示し、この位置検出装置Ａは、モータ機構の可動部の位置に応じた信号を出力するセンサ部（信号生成手段）１０と、このセンサ部１０からの信号に所定の演算処理を行うことによってモータ機構の可動部の絶対位置を検出する演算処理部（演算処理手段）２０と、演算処理部２０により検出された絶対位置を出力する出力部３０とを主要構成要素として備えてなる。
【００２０】
センサ部１０は、サーボモータなどの制御モータＲの回転軸１の後端に軸心を一致させて装着された第１および第２の歯車２、３と、各歯車２、３にそれぞれ対向させて配設されている第１および第２の磁気ユニット１１、１２とを備えてなるものとされる。ここで、各歯車２、３の歯形は、後述する磁気抵抗素子ブロック１３の各磁気抵抗素子１４（図３参照）により得られる電圧波形が近似的に正弦波となるように形成されている。
【００２１】
各歯車２、３の歯数は、第１歯車２の歯数Ｍと第２歯車３の歯数Ｎとが１だけ相違するものとされ（例えば、Ｍ＝５０，Ｎ＝５１）、第１歯車２の歯数Ｍは、この実施形態１では、回転軸１回転当たりのモータＲの電気的サイクル数の整数分の１とされていればよい。例えば、モータＲの電気的サイクル数が５０であれば、歯数Ｍが５０（５０／１）、２５（５０／２）または１０（５０／５）とされ、歯数Ｎが５１もしくは４９、２６もしくは２４または１１もしくは９とされていればよい。
【００２２】
また、各歯車２、３は、図２に示すように、１つの歯面がピッチ点Ｐで回転軸１の回転方向に並ぶよう回転軸１に装着される。
【００２３】
図３に、各磁気ユニット１１、１２の詳細構成を示す。なお、各磁気ユニット１１、１２は同様構成であるため、第１磁気ユニット１１を主として説明し、第２磁気ユニット１２の各構成要素は符号に（）付して付帯的に説明する。
【００２４】
磁気ユニット１１（１２）は、歯車２（３）の歯面に磁極を向けて配設されている永久磁石４と、この永久磁石４の磁極の前方、つまり永久磁石４と歯車２（３）との間に並列的に配設されている磁気抵抗素子ブロック１３を構成している２個の磁気抵抗素子（以下、単に素子という）１４、すなわち第１素子１４Ａ（１４Ｃ）および第２素子１４Ｂ（１４Ｄ）とを備えてなるものとされる。
【００２５】
ここで、この素子１４は、よく知られているように透過する磁束の変化に応じて電気抵抗が変化する特性を有する素子とされる。そして、この第１素子１４Ａ（１４Ｃ）および第２素子１４Ｂ（１４Ｄ）は、互いに歯車２（３）の１／４ピッチずれた位置に相対するように配設され、歯車２（３）が回転することにより生ずる透過磁束の変化に応じて、位相が１／４波長ずれた２つの正弦波状の電圧信号を得るよう回路構成されている（このような回路構成として、例えば特許第３０５８４０６号公報参照）。
【００２６】
例えば、歯車２（３）の矢印５の方向への回転を考えたときに、第１素子１４Ａ（１４Ｃ）の出力信号が正弦波信号となり、第２素子１４Ｂ（１４Ｄ）の出力信号が余弦波信号となるよう回路構成されている。
【００２７】
なお、磁気抵抗素子ブロック１３の素子数は２である必要はなく、検出精度を上げるために、例えば各素子１４Ａ（１４Ｃ）、１４Ｂ（１４Ｄ）の各々に対し、歯車２（３）の歯の半周期ずらした位置に各磁気抵抗素子を配置し、それら各磁気抵抗素子が各素子１４Ａ（１４Ｃ）、１４Ｂ（１４Ｄ）の出力信号を倍増するよう回路構成してもよい。
【００２８】
演算処理部２０は、ＣＰＵを中心としてＡ／Ｄ変換器、ＲＡＭ、ＲＯＭ、クロック、入出力インタフェースなどを備えてなるものとされる。このＲＯＭには後述するセンサ部１０により検出された電圧波形から回転位置を算出するためのプログラムなどが格納されている。また、ＲＡＭにはセンサ部１０からの検出値が一時的に格納される。そして、この演算処理部２０とセンサ部１０との信号のやりとりは、入出力インタフェースによりなされる。
【００２９】
図４に演算処理部２０の機能ブロック図を示す。
【００３０】
演算処理部２０は、センサ部１０からの信号に基づいて絶対位置を概略的に演算する概略位置演算部２１と、概略位置演算部２１により概略的に演算された絶対位置情報により精確な絶対位置を演算する修正絶対位置演算部２２とから構成される。
【００３１】
出力部３０は、例えばデジタル表示装置などの出力装置３１とされる。
【００３２】
しかして、かかる構成の位置検出装置Ａは、以下に述べるようにして回転軸１の絶対位置を検出するための概略位置演算処理および修正絶対位置演算処理を行う。
【００３３】
概略位置演算処理
図２に示すように、各歯車２、３の１つの歯面がピッチ点Ｐで回転軸１の回転方向に並ぶポイントをＰ₀とし、このポイントＰ₀が、第１素子１４Ａに相対するときの回転軸１の位置を基準位置（原点）Ｏ（図５参照）として設定する。
【００３４】
基準位置Ｏからの回転軸１の回転角をθとすると、第１磁気ユニット１１の第１素子１４Ａの出力信号値Ｖ₁は下記式（１）で表すことができる。
【００３５】
Ｖ₁＝αsin（Ｍθ）＋β （１）
【００３６】
但し、αおよびβは、素子１４の出力特性や各素子１４Ａ、１４Ｂ、１４Ｃ、１４Ｄの回路構成などに応じて決まる係数である。以下、説明の簡単化のためにα＝１、β＝０として説明する。すなわち、
【００３７】
Ｖ₁＝sin（Ｍθ）（２）
とする。
【００３８】
このとき、第１磁気ユニット１１の第２素子１４Ｂの出力信号値Ｖ₂は下記式（３）で表すことができる。
【００３９】
Ｖ₂＝cos（Ｍθ）（３）
【００４０】
また、第２磁気ユニット１２の第１素子１４Ｃおよび第２素子１４Ｄの出力信号値Ｖ₃およびＶ₄はそれぞれ下記式（４）および式（５）で表すことができる。
【００４１】
Ｖ₃＝sin（Ｎθ）（４）
【００４２】
Ｖ₄＝cos（Ｎθ）（５）
【００４３】
式（２）〜式（４）によく知られている三角関数の公式を適用して、
【００４４】
sinθ＝sin（Ｎ−Ｍ）θ＝sin（Ｎθ）cos（Ｍθ）−cos（Ｎθ）sin（Ｍθ）＝Ｖ₃・Ｖ₂−Ｖ₄・Ｖ₁ （６）
【００４５】
cosθ＝cos（Ｎ−Ｍ）θ＝cos（Ｎθ）cos（Ｍθ）＋sin（Ｎθ）sin（Ｍθ）＝Ｖ₄・Ｖ₂＋Ｖ₃・Ｖ₁ （７）
【００４６】
式（６）および式（７）より、
【００４７】

【００４８】
したがって、式（８）に三角関数の逆変換を適用して回転軸１の絶対位置を検出することができる。
【００４９】
すなわち、概略位置演算部２１は、各素子１４Ａ、１４Ｂ、１４Ｃ、１４Ｄの出力信号値Ｖ₁、Ｖ₂、Ｖ₃、Ｖ₄から例えば位置検出装置Ａの始動直後にも回転軸１の絶対位置を概略的に演算することができる。
【００５０】
図５に、第１歯車２の歯数Ｍを５とし、第２歯車３の歯数Ｎを６とした場合の、各磁気ユニット１１，１２の第１素子１４Ａ，１４Ｃの出力信号Ｖ₁，Ｖ₃と、各素子１４Ａ、１４Ｂ、１４Ｃ、１４Ｄの出力信号Ｖ₁、Ｖ₂、Ｖ₃、Ｖ₄から合成される正弦波信号sinθおよび余弦波信号cosθとを示す。
【００５１】
次に、修正絶対位置演算部２２が行う修正絶対位置演算処理を説明する。
【００５２】
修正絶対位置演算処理
概略位置演算処理により概略的な絶対位置情報が取得されると、それにより、例えば第１磁気ユニット１１の第１素子１４Ａの出力信号Ｖ₁を用いて精確な回転軸１の絶対位置を演算することが可能となる。
【００５３】
例えば、概略位置演算処理により演算された絶対位置をθ₁（以下、概略絶対位置という、図５参照）とし、このときの第１素子１４Ａの出力信号Ｖ₁の信号値をＶ_1Aとすると、下記式（９）の方程式を解くことにより修正絶対位置候補θ_A1，θ_A2，…が取得される。
【００５４】
Ｖ_1A＝sin（Ｍθ）（θ：０≦θ≦２π）（９）
【００５５】
こうして取得される各修正絶対位置候補θ_A1，θ_A2，…の中で、概略絶対位置θ₁に一番近いものを精確な絶対位置（以下、修正絶対位置という）θ_Aとして選択する。
【００５６】
このようにして、一旦修正絶対位置θ_Aが同定されると、後は第１磁気ユニット１１の第１素子１４Ａの出力信号を用いてインクリメンタル式に回転軸１の絶対位置を検出することが可能となる。
【００５７】
これにより、レゾルバのように回転軸１の１回転を１周期の正弦波信号および余弦波信号で見渡して絶対位置を概略的に検出することができるとともに、回転軸１の１回転を細分化して表す正弦波状信号Ｖ₁に基づきアブソリュート式エンコーダを用いた場合と同等以上の精度で絶対位置を検出することが可能となる。
【００５８】
例えば、正弦波状信号Ｖ₁の１波長を８ビットのディジタル信号で表し得るだけの精度があれば、歯数Ｍを５０として１／（５０×２５６）＝１／１２８００の分解能を備えさせることができる。
【００５９】
以上、本発明を実施形態に基づいて説明してきたが、本発明はかかる実施形態に限定されるものではなく、種々改変が可能である。例えば、実施形態においては回転軸１の絶対位置を検出するものとしたが、回転軸１の回転を減速する減速機（不図示である）を備えたモータ機構において、その減速機の出力軸に実施形態の歯車２，３を装着して、当該出力軸の絶対位置を検出するよう構成することも可能である。
【００６０】
同様に、前記出力軸により駆動される被駆動部を備えたモータ機構において、その被駆動部に実施形態の歯車２，３を装着して、当該被駆動部の絶対位置を検出するよう構成することも可能である。
【００６１】
また、そのような被駆動部は回転駆動されるものに限られる必要はなく、回転軸ないしは出力軸に設けられるピニオンにより直線的に駆動される直動部材とすることも可能である。この場合、直動部材に移動範囲に亘って歯数が１相違する位置検出用の各ラックを形成し、各磁気ユニット１１，１２を実施形態と同様にして各ラックの歯面にそれぞれ対向させて設けるとともに、各ラックの歯形を、電圧信号として正弦波状の波形が各磁気ユニット１１，１２から出力されるように形成する。こうして、各磁気ユニット１１，１２から出力される２種類の周波数の各正弦波信号および各余弦波信号に対して実施形態と同様の処理を行い、直動部材の移動範囲内における絶対位置を検出することが可能となる。
【００６２】
さらに、位置検出用ラックおよび磁気ユニットを１つのみ設けるよう構成することも可能である。例えば、図６に示すように、直動部材６の移動範囲に亘って伸縮自在な素材で構成した１つの位置検出用ラック７を伸縮可能に設けるとともに、この位置検出用ラック７を移動方向ｘに引っ張って伸張する、マグネットプランジャや圧電素子から構成される伸張手段８を設けるようにする。この伸張手段８が位置検出用ラック７を伸張させる長さは、位置検出用ラック７の歯数が移動範囲内で１を超えない所定数（１および小数を含む）ａだけ瞬時かつ瞬間的に減少するように設定される。
【００６３】
さらにまた、実施形態の各磁気ユニット１１，１２と同様の構成を有する磁気ユニット１１´の各素子１４Ａ´、１４Ｂ´が、伸張手段８による直動部材６の伸張前および伸張時の各状態において、ラック７の歯のピッチに対して１／４ピッチの間隔を設けて配設されるように、例えば各素子１４Ａ´、１４Ｂ´を直動部材６により支持して設けて、直動部材６の伸張と連動して各素子１４Ａ´、１４Ｂ´が移動するように構成する。
【００６４】
これにより、直動部材６の伸張前の各素子１４Ａ´、１４Ｂ´からの信号をそれぞれ正弦波信号Ｖ₁および余弦波信号Ｖ₂とし、直動部材６の伸張時の各素子１４Ａ´、１４Ｂ´からの信号をそれぞれ正弦波信号Ｖ₃および余弦波信号Ｖ₄として実施形態と同様の処理を実施することにより、直動部材６の絶対位置を検出することが可能となる。すなわち、各信号Ｖ₁、Ｖ₂、Ｖ₃、Ｖ₄から直動部材６の運動の１周期Ｔ以上の所定周期Ｔ／ａの正弦波信号sin（ａθ）および余弦波信号cos（ａθ）が生成され、これに基づき概略の絶対位置を演算するとともに、この概略の絶対位置情報により例えば信号Ｖ₁を用いて精確な絶対位置を検出することが可能となる。
【００６５】
この場合、例えば伸張手段８近傍の所定位置に直動部材６の伸び量を検出する公知のポテンショメータを設けて、その出力信号により前記所定数ａを補正するようにすれば、絶対位置を概略的に把握する際の誤差を小さくすることも可能となる。
【００６６】
また、伸張手段８は歯車に設けるようにすることも可能である。例えば、歯車２を歯形成部分のみが周方向に伸張可能なように形成するとともに、歯形成部分に伸張方向に対して斜めに切れ込みを入れ、伸張手段８により歯形成部分が伸張されたときに、歯が１を超えない所定数ａ重なり合うように構成する。これにより、直動部材６の場合と同様にして絶対位置を検出することが可能となる。
【００６７】
さらには、実施形態および前記各変形例におけるセンサ部１０は、前記特許公報にあるように、歯車またはラックに代えてリング状磁石等を用いて構成することももちろん可能である。
【００６８】
【発明の効果】
以上詳述したように、本発明によれば、モータ機構の可動部の位置を表す、２種類の周波数の各正弦波信号および各余弦波信号を用いて可動部の運動の１周期以上の所定周期を有する正弦波信号および余弦波信号を生成し、この正弦波信号および余弦波信号に基づいて絶対位置を概略的に検出するとともに、該概略的に把握された絶対位置情報に依り前記２種類の周波数の各正弦波信号および各余弦波信号の中の少なくとも１つの信号に基づき精確な絶対位置を検出算するようにしているので、安価な機構により常時精確にモータ機構の可動部の絶対位置を検出することができるという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る位置検出装置の概略構成を示すブロック図である。
【図２】各歯車の構成を示す模式図である。
【図３】磁気ユニットの詳細構成を示す模式図である。
【図４】演算処理部の詳細構成を示すブロック図である。
【図５】絶対位置検出の原理を説明するための模式図である。
【図６】実施形態の変形例を示す概略図である。
【符号の説明】
Ａ位置検出装置
Ｏ基準位置（原点）
Ｐピッチ点
Ｒモータ
１回転軸
２、３歯車
４磁石
８伸張手段
１０センサ部
１１、１２磁気ユニット
１４磁気抵抗素子
２０演算処理部
２１概略位置演算部
２２修正絶対位置演算部
３０出力部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a position detection method and a position detection apparatus. More specifically, a position detection method for detecting an absolute position of a movable part of a motor mechanism including a movable part such as a rotor of a motor, a rotating shaft and an output shaft, and a driven part driven by the movable part of the motor, and The present invention relates to a position detection device.
[0002]
[Prior art]
Conventionally, rotary encoders, resolvers, pulse generators, and the like have been widely used as position sensors for detecting the rotational position of a control motor such as a servo motor.
[0003]
Rotary encoders are classified into incremental type and absolute type. The former incremental method detects the absolute position of the moving part by detecting the reference position (origin) and measuring the amount of rotation of the rotor from this reference position. There is a drawback that the absolute position is not known until is detected. On the other hand, the absolute type of the latter can always detect the absolute position, but it is necessary to use the number of detection points (usually 8 to 12 channels) according to the required resolution, and the mechanism becomes complicated and the cost increases. There is a problem of becoming a factor.
[0004]
Since the resolver is configured to detect an absolute position by generating an analog sine wave signal in which one rotation of the motor corresponds to one cycle, the detection accuracy greatly depends on the accuracy of the sine wave signal to be generated. However, there is a problem that accurate absolute position detection cannot be performed unless the manufacturing accuracy is high.
[0005]
The system using the pulse generator has the same drawbacks as the incremental encoder.
[0006]
As described above, each of the various position detection methods and methods conventionally performed has advantages and disadvantages.
[0007]
Here, it can be said that the ideal position detection method or method is a position detection method or method that has high accuracy like an absolute encoder and low cost like a pulse generator.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art, and provides a position detection method and a position detection apparatus that can always detect the absolute position of a motor mechanism with a highly accurate and low-cost mechanism. It is aimed.
[0009]
[Means for Solving the Problems]
The position detection method of the present invention is provided with signal generating means for generating each sine wave voltage signal and each cosine wave voltage signal of two kinds of frequencies representing the position of the movable part of the motor mechanism, and one cycle of movement of the movable part. The two types of frequencies are set so that the number of waves of each sine wave voltage signal and each cosine wave voltage signal generated by the signal generating means in 1 is different within a range not exceeding 1 or 1. In the position detection method for detecting the absolute position of the movable part based on each sine wave voltage signal and each cosine wave voltage signal of the frequency of the above, from each sine wave voltage signal and each cosine wave voltage signal of the two types of frequencies A sine wave voltage signal and a cosine wave voltage signal having a predetermined period of one cycle or more of the movement of the movable part are generated, and an approximate value of the absolute position is detected based on the sine wave voltage signal and the cosine wave voltage signal, and then A corrected absolute position candidate satisfying the voltage value of the sine wave voltage signal or cosine wave voltage signal at the time of detection is selected, and then the candidate closest to the approximate value is selected from the corrected absolute position candidates. characterized by a.
[0011]
The position detection apparatus of the present invention is a position detection apparatus that detects the absolute position of the movable part of the motor mechanism, and includes a signal generation means and an arithmetic processing means, and the signal generation means is one of the movements of the movable part. the number of waves is different in a range not exceeding 1 or 1 in the periodic, it generates two types of the sine-wave voltage signals and the cosine wave voltage signal of frequency, the arithmetic processing means, each of the two kinds of frequencies Based on the sine wave voltage signal and the cosine wave voltage signal, a sine wave voltage signal and a cosine wave voltage signal having a predetermined period of one or more periods of the movement of the movable part are generated from the sine wave voltage signal and each cosine wave voltage signal. An approximate value of the absolute position is detected, and then a corrected absolute position candidate that satisfies the voltage value of the sine wave voltage signal or cosine wave voltage signal at the time of detection is selected, and then the corrected absolute position candidate is selected from the corrected absolute position candidates. A candidate closest to the approximate value is set as an accurate absolute position .
[0013]
Further, in the position detection device of the present invention, for example, the signal generation unit includes each gear having a different number of teeth mounted on the movable portion and each magnetic unit disposed to face the teeth of each gear. Each of the magnetic units includes a magnet arranged with a magnetic pole facing the corresponding gear teeth, and a pitch of the gear teeth between the magnet and the corresponding gear teeth. Two magnetoresistive elements arranged at intervals of / 4 pitch, and the tooth profile of each gear is formed so as to output a sinusoidal voltage waveform as a voltage signal, and the magnetoresistive element The element is circuit-configured to obtain two sinusoidal voltage signals having a phase shift of ¼ wavelength as a sine wave signal and a cosine wave signal in response to a change in transmitted magnetic flux caused by rotation of each gear. , The arithmetic processing means includes each magnet Using two respective sinusoidal voltage signals and the cosine wave voltage signal having a frequency of from knit, it generates a sinusoidal voltage signal and a cosine-wave voltage signal of movement of the same cycle of the movable portion, the sinusoidal voltage The absolute position of the movable part is detected based on the signal and the cosine wave voltage signal. In this case, each gear may be mounted on the rotation shaft of the motor, and the motor mechanism may include a speed reducer that reduces the rotation of the rotor, and each gear may be mounted on the output shaft of the speed reducer. The motor mechanism may include a driven part that is driven by a rotating shaft or an output shaft, and each gear may be mounted on the driven part.
[0014]
Furthermore, in the position detection device of the present invention, for example, the driven part is a linear motion member that is linearly driven within a predetermined range by the rotation of the motor, and the signal generating means is placed in the predetermined range on the linear motion member. Each of the position detection racks provided so that the number of teeth is different from each other, and each of the magnetic units disposed to face the teeth of each of the racks. Two magnets arranged with a magnetic pole facing each other, and a gap of 1/4 pitch with respect to the pitch of the teeth of the rack between the magnet and the teeth of the corresponding rack And the tooth profile of each rack is formed so that a sine-wave voltage waveform is output as a voltage signal, and the magnetoresistive element transmits a magnetic flux generated by the movement of each rack. In response to changes in The phases were circuitry configured to obtain two sinusoidal voltage signals shifted 1/4 wavelength as a sine wave signal and cosine wave signal, the arithmetic processing means, two respective sinusoidal voltage signal from the magnetic unit And each cosine wave voltage signal is used to generate a sine wave voltage signal and a cosine wave voltage signal having the same period as the movement of the linear motion member, and based on the sine wave voltage signal and the cosine wave voltage signal, The approximate absolute position of the moving member may be detected.
[0015]
Further, in the position detection device of the present invention, for example, the signal generating means includes a telescopic rack provided on the linear motion member, an extension means for extending the linear motion member in the movement direction, and teeth of the rack. The extension means instantaneously moves the linear motion member so that the number of teeth of the rack is reduced to a predetermined number not exceeding 1 or 1 within the expansion / contraction range of the rack. The magnetic unit is disposed between a magnet having a magnetic pole opposed to a rack tooth, and between the magnet and the rack tooth, before and during extension by the extension means. Two magnetoresistive elements provided so as to be arranged at an interval of 1/4 pitch with respect to the pitch of the rack teeth in each state, and the tooth shape of the rack is sinusoidal as a voltage signal The voltage waveform is In response to a change in transmitted magnetic flux caused by the movement of the rack, the magnetoresistive element converts two sinusoidal voltage signals whose phases are shifted by ¼ wavelength into sine wave signals and The circuit is configured to obtain a cosine wave signal, and the arithmetic processing means has two frequency sine wave voltage signals generated from the magnetic unit before and after the linear motion member is extended by the extension means, and Using each cosine wave voltage signal, a sine wave voltage signal and a cosine wave voltage signal having a predetermined period that is equal to or greater than the period of the movement of the linear motion member are generated, and the linear wave signal is generated based on the sine wave voltage signal and the cosine wave voltage signal. The absolute position of the moving member may be calculated roughly. In this case, an extension amount detecting means for detecting the extension amount of the linear motion member by the extension means is provided, and the predetermined number of rack teeth decreasing is corrected according to the detection result of the extension amount detecting means. preferable.
[0016]
Further, in the position detection device of the present invention, for example, the signal generating means includes a gear mounted on the movable portion, an extension means for extending a tooth forming portion of the gear in the circumferential direction, and a tooth of the gear. The gear has a notch obliquely with respect to a circumferential direction in the tooth forming portion, and the extension means reduces the predetermined number of teeth of the gear not exceeding one. The tooth-forming portion of the gear is instantaneously extended in the circumferential direction, and the magnetic unit includes a magnet having a magnetic pole disposed opposite to the gear teeth, and between the magnet and the gear teeth. In conjunction with the extension of the gear by the extension means so as to be arranged at intervals of 1/4 pitch with respect to each pitch of the gear teeth in the respective states before and after extension by the extension means. Two magnetic resistors provided to And the magnetoresistive element converts two sinusoidal voltage signals whose phases are shifted by a quarter wavelength in response to a change in transmitted magnetic flux caused by rotation of the gear. The circuit is configured to obtain a cosine wave signal, and the approximate position calculation means includes two sine wave voltage signals of two frequencies from the magnetic unit in each state before and after the extension of the gear by the extension means, and Using the cosine wave voltage signal, a sine wave voltage signal and a cosine wave voltage signal having a predetermined period equal to or greater than the period of the movement of the movable part are generated, and the movable part of the movable part is generated based on the sine wave voltage signal and the cosine wave voltage signal. The absolute position may be calculated roughly. In this case, it is preferable that an extension amount detection means for detecting the extension amount of the gear by the extension means is provided, and the predetermined number of reduction of the gear teeth is corrected according to the detection result of the extension amount detection means. .
[0017]
[Action]
Since the present invention is configured as described above, the absolute position of the movable portion of the motor mechanism can always be accurately detected based on the sine wave signals and the cosine wave signals of two types of frequencies.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the present invention is explained based on an embodiment, referring to an accompanying drawing, the present invention is not limited only to this embodiment.
[0019]
FIG. 1 shows a schematic configuration of a position detection device to which a position detection method according to an embodiment of the present invention is applied. This position detection device A outputs a signal corresponding to the position of a movable portion of a motor mechanism. (Signal generating means) 10, an arithmetic processing section (arithmetic processing means) 20 for detecting the absolute position of the movable part of the motor mechanism by performing predetermined arithmetic processing on the signal from the sensor section 10, and an arithmetic processing section 20 The output unit 30 that outputs the absolute position detected by the above is provided as a main component.
[0020]
The sensor unit 10 is opposed to the first and

second gears

2 and 3 mounted on the rear end of the rotary shaft 1 of the control motor R such as a servo motor so that the shaft centers thereof coincide with each other and the

gears

2 and 3, respectively. The first and second magnetic units 11 and 12 are provided. Here, the tooth shapes of the

gears

2 and 3 are formed so that the voltage waveform obtained by each magnetoresistive element 14 (see FIG. 3) of the magnetoresistive element block 13 described later is approximately a sine wave.
[0021]
The number of teeth of each

gear

2 and 3 is such that the number of teeth M of the first gear 2 and the number of teeth N of the second gear 3 are different by 1 (for example, M = 50, N = 51). In the first embodiment, the number of teeth M of the gear 2 may be set to 1 / integer of the number of electrical cycles of the motor R per one rotation of the rotating shaft. For example, if the number of electrical cycles of the motor R is 50, the number of teeth M is 50 (50/1), 25 (50/2) or 10 (50/5), and the number of teeth N is 51 or 49, It may be 26 or 24 or 11 or 9.
[0022]
Further, as shown in FIG. 2, the

gears

2 and 3 are attached to the rotary shaft 1 so that one tooth surface is aligned at the pitch point P in the rotational direction of the rotary shaft 1.
[0023]
FIG. 3 shows a detailed configuration of each of the magnetic units 11 and 12. Since each of the magnetic units 11 and 12 has the same configuration, the first magnetic unit 11 will be mainly described, and each component of the second magnetic unit 12 will be supplementarily described by adding () to the reference numeral.
[0024]
The magnetic unit 11 (12) includes a permanent magnet 4 disposed with a magnetic pole facing the tooth surface of the gear 2 (3), and in front of the magnetic pole of the permanent magnet 4, that is, the permanent magnet 4 and the gear 2 (3). Two magnetoresistive elements (hereinafter simply referred to as elements) 14 constituting the magnetoresistive element block 13 disposed in parallel with each other, that is, the first element 14A (14C) and the second element 14B. (14D).
[0025]
Here, as is well known, the element 14 is an element having a characteristic that the electric resistance changes in accordance with a change in the transmitted magnetic flux. The first element 14A (14C) and the second element 14B (14D) are arranged so as to face each other at a position shifted by 1/4 pitch of the gear 2 (3), and the gear 2 (3) rotates. The circuit is configured to obtain two sinusoidal voltage signals whose phases are shifted by a quarter wavelength in accordance with the change in the transmitted magnetic flux generated by this (see, for example, Japanese Patent No. 3058406 as such a circuit configuration). ).
[0026]
For example, when considering the rotation of the gear 2 (3) in the direction of the arrow 5, the output signal of the first element 14A (14C) becomes a sine wave signal, and the output signal of the second element 14B (14D) becomes a cosine wave. The circuit is configured to be a signal.
[0027]
The number of elements of the magnetoresistive element block 13 does not have to be two, and in order to increase the detection accuracy, for example, for each of the elements 14A (14C) and 14B (14D), the teeth of the gear 2 (3) Each magnetoresistive element may be arranged at a position shifted by a half cycle, and each magnetoresistive element may be configured to double the output signal of each element 14A (14C), 14B (14D).
[0028]
The arithmetic processing unit 20 includes an A / D converter, a RAM, a ROM, a clock, an input / output interface, and the like with a CPU at the center. The ROM stores a program for calculating a rotational position from a voltage waveform detected by the sensor unit 10 described later. Further, the detection value from the sensor unit 10 is temporarily stored in the RAM. The exchange of signals between the arithmetic processing unit 20 and the sensor unit 10 is performed by an input / output interface.
[0029]
FIG. 4 shows a functional block diagram of the arithmetic processing unit 20.
[0030]
The arithmetic processing unit 20 includes an approximate position calculating unit 21 that approximately calculates an absolute position based on a signal from the sensor unit 10, and an accurate absolute position based on absolute position information that is approximately calculated by the approximate position calculating unit 21. It is comprised from the correction absolute position calculating part 22 which calculates.
[0031]
The output unit 30 is an output device 31 such as a digital display device.
[0032]
Therefore, the position detection apparatus A having such a configuration performs a rough position calculation process and a corrected absolute position calculation process for detecting the absolute position of the rotary shaft 1 as described below.
[0033]
As shown in FIG. 2, a point where one tooth surface of each of the

gears

2 and 3 is arranged at the pitch point P in the rotation direction of the rotary shaft 1 is P _0, and this point P ₀ is the first element 14A. Is set as the reference position (origin) O (see FIG. 5).
[0034]
When the rotation angle of the rotary shaft 1 from the reference position O is θ, the output signal value V ₁ of the first element 14A of the first magnetic unit 11 can be expressed by the following formula (1).
[0035]
V ₁ = αsin (Mθ) + β (1)
[0036]
However, α and β are coefficients determined according to the output characteristics of the element 14, the circuit configurations of the

elements

14A, 14B, 14C, and 14D. In the following description, α = 1 and β = 0 will be described for the sake of simplicity. That is,
[0037]
V ₁ = sin (Mθ) (2)
And
[0038]
At this time, the output signal value V ₂ of the second element 14B of the first magnetic unit 11 can be expressed by the following equation (3).
[0039]
V ₂ = cos (Mθ) (3)
[0040]
The output signal values V ₃ and V ₄ of the first element 14C and the second element 14D of the second magnetic unit 12 can be expressed by the following expressions (4) and (5), respectively.
[0041]
V ₃ = sin (Nθ) (4)
[0042]
V ₄ = cos (Nθ) (5)
[0043]
Applying the well-known trigonometric formula to equations (2) to (4),
[0044]
sin θ = sin (N−M) θ = sin (Nθ) cos (Mθ) −cos (Nθ) sin (Mθ) = V ₃ · V ₂ −V ₄ · V ₁ (6)
[0045]
cos θ = cos (N−M) θ = cos (Nθ) cos (Mθ) + sin (Nθ) sin (Mθ) = V ₄ · V ₂ + V ₃ · V ₁ (7)
[0046]
From Equation (6) and Equation (7),
[0047]

[0048]
Therefore, the absolute position of the rotating shaft 1 can be detected by applying the inverse transformation of the trigonometric function to the equation (8).
[0049]
That is, the approximate position calculation unit 21 determines the absolute position of the rotary shaft 1 from the output signal values V ₁ , V ₂ , V ₃ , V _{4 of} each

element

14A, 14B, 14C, 14D, for example, immediately after the position detector A is started. Can be calculated roughly.
[0050]
In FIG. 5, when the number of teeth M of the first gear 2 is set to 5 and the number of teeth N of the second gear 3 is set to 6, the output signals V ₁ of the

first elements

14A and 14C of the magnetic units 11 and 12 V ₃ and a sine wave signal sin θ and a cosine wave signal cos θ synthesized from the output signals V ₁ , V ₂ , V ₃ , and V _{4 of the} elements 14A, 14B, 14C, and 14D are shown.
[0051]
Next, the corrected absolute position calculation process performed by the corrected absolute position calculation unit 22 will be described.
[0052]
Schematically absolute position information by modifying the absolute position computing processing rough position calculation process is obtained, thereby, for example, the output signal V ₁ precise rotary shaft 1 by using the first element 14A of the first magnetic unit 11 An absolute position can be calculated.
[0053]
For example, if the absolute position calculated by the approximate position calculation process is θ ₁ (hereinafter referred to as the approximate absolute position, see FIG. 5), and the signal value of the output signal V ₁ of the first element 14A at this time is V _1A , The corrected absolute position candidates θ _A1 , θ _A2 ,... _Are obtained by solving the equation (9) below.
[0054]
V _1A = sin (Mθ) (θ: 0 ≦ θ ≦ 2π) (9)
[0055]
Among the corrected absolute position candidates θ _A1 , θ _A2 ,... Thus acquired, the one closest to the approximate absolute position θ ₁ is selected as an accurate absolute position (hereinafter referred to as a corrected absolute position) θ _A.
[0056]
In this way, once the corrected absolute position θ _A is identified, it is possible to detect the absolute position of the rotary shaft 1 incrementally using the output signal of the first element 14A of the first magnetic unit 11 thereafter. It becomes.
[0057]
This makes it possible to roughly detect one rotation of the rotating shaft 1 with a sine wave signal and cosine wave signal of one cycle as in a resolver, and to roughly detect the absolute position, and to subdivide one rotation of the rotating shaft 1. Based on the sinusoidal signal V ₁ represented, it is possible to detect the absolute position with an accuracy equal to or higher than when an absolute encoder is used.
[0058]
For example, if there is an accuracy sufficient to represent one wavelength of the sinusoidal signal V ₁ as an 8-bit digital signal, the number of teeth M is 50 and a resolution of 1 / (50 × 256) = 1/12800 is provided. it can.
[0059]
As mentioned above, although this invention has been demonstrated based on embodiment, this invention is not limited to this embodiment, A various change is possible. For example, in the embodiment, the absolute position of the rotary shaft 1 is detected. However, in a motor mechanism including a speed reducer (not shown) that decelerates the rotation of the rotary shaft 1, the output shaft of the speed reducer It is also possible to install the

gears

2 and 3 of the embodiment and detect the absolute position of the output shaft.
[0060]
Similarly, in a motor mechanism including a driven part driven by the output shaft, the

gears

2 and 3 of the embodiment are mounted on the driven part, and the absolute position of the driven part is detected. It is also possible.
[0061]
Further, such a driven part is not necessarily limited to one that is rotationally driven, and may be a linearly driven member that is linearly driven by a pinion provided on a rotating shaft or an output shaft. In this case, the position detecting racks having the number of teeth different by 1 over the moving range are formed on the linear motion member, and the magnetic units 11 and 12 are respectively opposed to the tooth surfaces of the racks similarly to the embodiment. In addition, the tooth profile of each rack is formed so that a sinusoidal waveform is output from each of the magnetic units 11 and 12 as a voltage signal. In this way, the same processing as that of the embodiment is performed on each sine wave signal and each cosine wave signal output from each of the magnetic units 11 and 12, and the absolute position within the moving range of the linear motion member is detected. It becomes possible to do.
[0062]
Furthermore, it is possible to provide only one position detection rack and one magnetic unit. For example, as shown in FIG. 6, one position detection rack 7 made of a material that can be expanded and contracted over the moving range of the linear motion member 6 is provided to be extendable and the position detection rack 7 is moved in the moving direction x. An extension means 8 composed of a magnet plunger or a piezoelectric element that is pulled and extended is provided. The length by which the extension means 8 extends the position detection rack 7 is instantaneously and instantaneously by a predetermined number (including 1 and decimal number) a in which the number of teeth of the position detection rack 7 does not exceed 1 within the movement range. Set to decrease.
[0063]
Furthermore, the elements 14A ′ and 14B ′ of the magnetic unit 11 ′ having the same configuration as the magnetic units 11 and 12 of the embodiment are in the respective states before and when the linear motion member 6 is expanded by the expansion means 8. For example, each element 14A ′, 14B ′ is supported and provided by the linear motion member 6 so as to be disposed at an interval of 1/4 pitch with respect to the tooth pitch of the rack 7. Each element 14A ', 14B' is configured to move in conjunction with the expansion of the.
[0064]
As a result, the signals from the elements 14A ′ and 14B ′ before expansion of the linear motion member 6 are set as a sine wave signal V ₁ and a cosine wave signal V ₂ , respectively, and the elements 14A ′ and 14B when the linear motion member 6 is expanded. It is possible to detect the absolute position of the linear motion member 6 by performing the same processing as that of the embodiment as the sine wave signal V ₃ and the cosine wave signal V ₄ as signals from '. That is, a sine wave signal sin (aθ) and a cosine wave signal cos (aθ) having a predetermined cycle T / a that is one cycle T or more of the movement of the linear motion member 6 from the signals V ₁ , V ₂ , V ₃ , V _4. The approximate absolute position is calculated based on the generated absolute position information, and the accurate absolute position can be detected by using the approximate absolute position information, for example, using the signal V ₁ .
[0065]
In this case, for example, if a known potentiometer for detecting the extension amount of the linear motion member 6 is provided at a predetermined position in the vicinity of the extension means 8 and the predetermined number a is corrected by the output signal, the absolute position can be approximated. It is also possible to reduce the error in grasping.
[0066]
Further, the extension means 8 can be provided on the gear. For example, when the gear 2 is formed so that only the tooth forming portion can be extended in the circumferential direction, the tooth forming portion is cut obliquely with respect to the extending direction, and the tooth forming portion is extended by the extending means 8. The teeth are configured to overlap a predetermined number a that does not exceed 1. Thereby, the absolute position can be detected in the same manner as in the case of the linear motion member 6.
[0067]
Furthermore, as described in the above-mentioned patent publication, the sensor unit 10 in the embodiment and each of the modifications may be configured using a ring magnet or the like instead of a gear or a rack.
[0068]
【The invention's effect】
As described above in detail, according to the present invention, a predetermined period of one or more cycles of the movement of the movable part using each sine wave signal and each cosine wave signal of two kinds of frequencies representing the position of the movable part of the motor mechanism. A sine wave signal and a cosine wave signal having a period are generated, the absolute position is roughly detected based on the sine wave signal and the cosine wave signal, and the two types are determined based on the roughly grasped absolute position information. Since an accurate absolute position is detected and calculated based on at least one of each sine wave signal and each cosine wave signal of the frequency, the absolute position of the movable part of the motor mechanism is always accurately and accurately by an inexpensive mechanism. An excellent effect that can be detected.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a position detection apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of each gear.
FIG. 3 is a schematic diagram showing a detailed configuration of a magnetic unit.
FIG. 4 is a block diagram illustrating a detailed configuration of an arithmetic processing unit.
FIG. 5 is a schematic diagram for explaining the principle of absolute position detection.
FIG. 6 is a schematic diagram showing a modification of the embodiment.
[Explanation of symbols]
A Position detection device O Reference position (origin)
P Pitch point R Motor 1

Rotating shaft

2, 3 Gear 4 Magnet 8 Extending means 10 Sensor unit 11, 12 Magnetic unit 14 Magnetoresistive element 20 Arithmetic processing unit 21 Approximate position calculating unit 22 Corrected absolute position calculating unit 30 Output unit

Claims

Signal generating means for generating each sine wave voltage signal and each cosine wave voltage signal having two types of frequencies representing the position of the movable part of the motor mechanism is provided, and the signal generating means is generated in one cycle of movement of the movable part. The two types of frequencies are set so that the number of waves of each sine wave voltage signal and each cosine wave voltage signal does not exceed 1 or 1, and each sine wave voltage signal of the two types of frequencies is set. In the position detection method for detecting the absolute position of the movable part based on each cosine wave voltage signal ,
A sine wave voltage signal and a cosine wave voltage signal having a predetermined period of one or more periods of movement of the movable part are generated from the sine wave voltage signal and the cosine wave voltage signal of the two types of frequencies, and the sine wave voltage signal and An approximate value of the absolute position is detected based on the cosine wave voltage signal, and then a corrected absolute position candidate that satisfies the voltage value of the sine wave voltage signal or cosine wave voltage signal at the time of detection is selected, and then the corrected absolute position is selected. A position detection method, wherein a candidate closest to the approximate value among the position candidates is set as an accurate absolute position .

A position detection device for detecting an absolute position of a movable part of a motor mechanism,
A signal generating means and an arithmetic processing means,
The signal generating means generates each sine wave voltage signal and each cosine wave voltage signal having two different frequencies within a range in which the number of waves in one cycle of movement of the movable part does not exceed 1 or 1.
The arithmetic processing means generates a sine wave voltage signal and a cosine wave voltage signal having a predetermined period of one or more periods of movement of the movable part from the sine wave voltage signal and the cosine wave voltage signal of the two types of frequencies, Based on the sine wave voltage signal and the cosine wave voltage signal, an approximate value of the absolute position is detected, and then a corrected absolute position candidate that satisfies the voltage value of the sine wave voltage signal or the cosine wave voltage signal at the time of detection is selected. Then, a position closest to the approximate value among the corrected absolute position candidates is set as an accurate absolute position .

The signal generating means includes gears with different numbers of teeth mounted on the movable part, and magnetic units respectively disposed opposite to the teeth of the gears,
Each of the magnetic units has a quarter of the pitch of the gear teeth between the magnet and the corresponding gear teeth, and a magnet disposed with the magnetic poles facing the corresponding gear teeth. Two magnetoresistive elements arranged with a pitch interval,
The tooth shape of each gear is formed so that a sinusoidal voltage waveform is output as a voltage signal, and the magnetoresistive element has a phase of 1 in accordance with a change in transmitted magnetic flux caused by the rotation of each gear. / 4 is configured to obtain two sinusoidal voltage signals shifted by four wavelengths as a sine wave signal and a cosine wave signal,
The arithmetic processing means uses each sine wave voltage signal and each cosine wave voltage signal of two types of frequencies from each magnetic unit to use a sine wave voltage signal and a cosine wave voltage signal having the same period as the movement period of the movable part. The position detecting device according to claim 2, wherein the absolute position of the movable portion is detected based on the sine wave voltage signal and the cosine wave voltage signal.

4. The position detecting device according to claim 3 , wherein each gear is mounted on a rotating shaft of a motor.

4. The position detecting device according to claim 3 , wherein the motor mechanism includes a speed reducer that decelerates the rotation of the rotor, and each gear is mounted on an output shaft of the speed reducer.

4. The position detection apparatus according to claim 3 , wherein the motor mechanism includes a driven portion driven by a rotating shaft or an output shaft, and each gear is mounted on the driven portion.

The driven part is a linear member that is linearly driven within a predetermined range by rotation of the motor, and the signal generating means is provided on the linear member so that the number of teeth is different from one another over the predetermined range. Each position detection rack, and each magnetic unit disposed opposite to the teeth of each rack, each magnetic unit including a magnet disposed with a magnetic pole facing the corresponding rack tooth; Two magnetoresistive elements disposed at intervals of ¼ pitch with respect to the pitch of the teeth of the rack between the magnet and the teeth of the corresponding rack, The tooth profile is formed so that a sinusoidal voltage waveform is output as a voltage signal, and the phase of the magnetoresistive element is shifted by a quarter wavelength according to the change in transmitted magnetic flux caused by the movement of each rack. Two sinusoidal voltage signals Is circuitry configured to obtain a sine wave signal and a cosine wave signal, the arithmetic processing means, using two respective sinusoidal voltage signals and the cosine-wave voltage signal from the magnetic unit, movement of the linear motion member And generating a sine wave voltage signal and a cosine wave voltage signal having the same period as that of the sine wave, and detecting a rough absolute position of the linear motion member based on the sine wave voltage signal and the cosine wave voltage signal. Item 3. The position detection device according to Item 2 .

The signal generating means includes a telescopic rack provided on the linear motion member, an expansion means for extending the linear motion member in the moving direction, and a magnetic unit disposed to face the teeth of the rack, and the expansion means However, the linear motion member is instantaneously extended so that the number of teeth of the rack is reduced to a predetermined number not exceeding 1 or 1 within the expansion / contraction range of the rack, and the magnetic unit includes a magnetic pole Between the magnet and the teeth of the rack between the magnet and the teeth of the rack, and 1 for the pitch of the rack teeth before and after the extension by the extension means. / 4 pitches, and the rack tooth profile is formed to output a sinusoidal voltage waveform as a voltage signal, and the magnetic The resistive element is in front The circuit is configured so as to obtain two sinusoidal voltage signals having a phase shift of ¼ wavelength as a sine wave signal and a cosine wave signal in accordance with a change in transmitted magnetic flux generated by the movement of the rack, and the arithmetic processing means The movement of the linear motion member using the sine wave voltage signal and the cosine wave voltage signal of two types of frequencies generated from the magnetic unit in each state before and when the linear motion member is stretched by the stretching means. Generating a sine wave voltage signal and a cosine wave voltage signal having a predetermined period equal to or greater than the period, and roughly calculating the absolute position of the linear motion member based on the sine wave voltage signal and the cosine wave voltage signal. The position detecting device according to claim 2 .

The signal generation means includes a gear mounted on the movable part, an extension means for extending a tooth forming portion of the gear in a circumferential direction, and a magnetic unit disposed to face the gear teeth, the gear being The tooth forming portion has a notch obliquely with respect to the circumferential direction, and the extension means instantaneously extends the gear tooth forming portion in the circumferential direction so that the number of teeth of the gear decreases by a predetermined number not exceeding 1. The magnetic unit includes a magnet having a magnetic pole disposed opposite to the teeth of the gear, and each of the magnet before and after the extension by the extension means between the magnet and the teeth of the gear. Two magnetoresistive elements provided so as to be interlocked with the extension of the gear by the extension means so as to be arranged at intervals of ¼ pitch with respect to each pitch of the gear teeth in the state. The magnetoresistive element and the gear A circuit configured to obtain two sinusoidal voltage signals whose phases are shifted by ¼ wavelength as the sine wave signal and the cosine wave signal in accordance with a change in transmitted magnetic flux generated by Using the sine wave voltage signals and the cosine wave voltage signals of two kinds of frequencies from the magnetic unit in the respective states before and after the extension of the gear by the extension means, and more than the period of movement of the movable part claim 2 of generating a sinusoidal voltage signal and a cosine-wave voltage signal having a predetermined period, characterized by schematically calculating the absolute position of the movable portion on the basis of the sine wave voltage signal and the cosine wave voltage signal The position detection device described.

9. The apparatus according to claim 8 , further comprising an extension amount detection unit that detects an extension amount of the linear motion member by the extension unit, and correcting a predetermined number in which the rack teeth decrease in accordance with a detection result of the extension amount detection unit. Position detection device.

10. The apparatus according to claim 9, further comprising an extension amount detecting means for detecting an extension amount of the gear by the extension means, and correcting a predetermined number in which the gear teeth decrease in accordance with a detection result of the extension amount detecting means. Position detection device.