JP2005043070A - Rotation detector and bearing having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detector that can be built into compact equipment, can detect a rotational angle precisely, and can calculate the rotational angle rapidly and accurately, and to provide a bearing having the rotation detector. <P>SOLUTION: The rotation detector comprises a magnetism generating means 3 for generating anisotropic magnetism to the circumferential direction around a rotation center; a magnetic line sensor 5 for detecting the magnetism of the magnetism generating means 3; and an angle calculating means 6 for calculating the rotational angle of the magnetism generating means 3 from the output detected by the magnetic line sensor 5. In the rotation detector, the magnetic line sensor 5 is arranged around the rotation center of the magnetism generating means 3 for one round, and the angle calculating means 6 reduces the influence of variations or noise in each element characteristic following the output detected by the magnetism line sensor 5 or an accompanying circuit, and can calculate the rotational angle of the magnetism generating means 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２５】
ここで、磁気ラインセンサ５における素子５ａの物理的配置が既知であれば、上記演算により求まった基本波の位相φに基づき磁気発生手段３の物理的角度Θの関係は所定の計算によって求めることができる。例えば角度算出部８において、基本波位相演算部７で求められた位相φと磁気発生手段３の物理的角度Θとの対応関係を変換テーブルとして記憶しておけば、当該磁気発生手段３の回転角度を容易に求めることができる。
【００２６】
上記演算内容に示すように、かかるフーリエ変換の演算方法による手法によれば各センサ素子５ａの座標値を使用しないため、処理回路である角度算出手段６を簡単な構成とすることができる。言い換えると、磁気ラインセンサ５で検出された出力に伴う各素子５ａの特性又は付随する回路のばらつき、或いはノイズの影響を低減しつつ（影響されず）磁気発生手段３の回転角度を検出することができるので、ばらつきやノイズを除去すべく別途の情報処理工程（例えば空間フィルタによるノイズ除去工程等）が不要となり、回転角度の算出をより素早く且つ正確に行うことができる。
【００２７】
次に、本発明に係る第２の実施形態について説明する。
本実施形態に係る回転検出装置は、第１の実施形態と同様、回転側部材１に配設された磁気発生手段３の回転角度を検出するためのもので、図２に示すように、磁気ラインセンサ５は矩形状に配置された磁気ラインセンサ列５Ａ〜５Ｄで構成され、それらにより囲まれた部位に角度算出手段６が形成されている。
【００２８】
ここで、本実施形態における角度算出手段６は、図５に示すように、磁気ラインセンサの検出値を磁界分布のゼロ付近で最も大きくなるように、且つ、ゼロから離れた位置では殆ど検出値がないように変換することにより、ゼロ付近に重みを持ったデータ列を作る重み付与部９と、該重み付与部９により作られたデータ列に基づいて２次元座標を用いた重心まわりのモーメント計算を行って磁気発生手段３の回転角度を算出する角度算出部１０とを有している。
【００２９】
例えば、主に画像処理において、画像での計測に使用される重心・主軸計算方法を用いることができる。即ち、本実施形態における角度算出手段６では、かかる重心・主軸計算方法を用いることとし、基本的には最小２乗誤差法により、データを質量と考えて慣性モーメントの計算を行い、それが最小になるようにして角度計算を行うものであり、具体的には以下の如き計算を行う。
【００３０】
まず、以下の演算によりセンサ出力の平均値を求め、これをゼロ値とする（図６（ａ）参照）。尚、各素子５ａ毎の出力をＳｉ、データの個数をＮ、ゼロ値をＳａｖｅとおいている。
【００３１】
【数２】

【００３２】
次に、平均値（ゼロ値）に近いほど大きな値となるよう以下の如き変換のための演算を行う（同図（ｂ）参照）。
【００３３】
【数３】

【００３４】
そして、例えば上記変換値又は固定値を引き算し、負の値になったら０にするなど、平均値（ゼロ値）から遠いデータはできるだけ小さな値に変換する（同図（ｃ）参照）
【００３５】
【数４】

【００３６】
上記のデータ変換を行った結果、ゼロラインに近いセンサ出力を主として、ゼロラインに近いほど重みをもったデータ列ができる。このデータ列に対して後述のモーメント計算を施した演算を行うと、図７に示すように、回転角度が検出できる。
【００３７】
即ち、同図で検出された直線を向き情報付きで定義した場合、図８に示すように、当該直線は角度Θと原点からの距離ｆで表すことができ、直線の向きの単位ベクトルｅ_ｉ、それと直交する単位ベクトルをｅ_ｆとすると、
ｅ_ｉ＝（ ｃｏｓθ ， ｓｉｎθ ）
ｅ_ｆ＝（ −ｓｉｎθ ， ｃｏｓθ ）
となり、直線はλを任意の値として、ｆｅ_ｆ＋λｅ_ｉと表すことができるとともに、当該直線と点Ｐ（ ｘ ， ｙ ）との距離は、

と表すことができる。
【００３８】
点Ｐ（ ｘ ， ｙ ）のデータがｍｉのとき、直線からのずれ量を以下のように計算し、それを評価値とする。かかる評価値は、既述した２乗誤差の和又は軸回りのモーメント計算と等価である。
【００３９】
【数５】

【００４０】
上記評価値Ｉは、Θ及びｆの関数となり、重心を通ってモーメントが最大又は最小な直線となったときに極値をとるものである。そして、
【００４１】
【数６】

【００４２】
となる条件を求めると以下のようになる。
【００４３】
【数７】

【００４４】
ここで、上記演算式中の各記号は以下の内容を示すものとする。
【００４５】
【数８】

【００４６】
更に、Ａ、Ｂ及びＣを以下の如く定義する。
【００４７】
【数９】

【００４８】
上記の如く定義したＡ、Ｂ及びＣより回転角度は以下のように求めることができる。
【００４９】
【数１０】

【００５０】
条件を指定してまとめると、以下のような結果が得られる。
【００５１】
【数１１】

【００５２】
本実施形態によれば、基本的に統計計算にて磁気発生手段３の回転角度を算出するので、素子５ａのばらつきやノイズの影響を受けにくく、また、２次元データとして処理することから、磁気発生手段３と磁気ラインセンサ５の素子５ａとの配置ずれによる悪影響をも回避することができる。
【００５３】
次に、本発明に係る第３の実施形態について説明する。
本実施形態に係る回転検出装置は、第１の実施形態と同様、回転側部材１に配設された磁気発生手段３の回転角度を検出するためのもので、図９に示すように、各磁気ラインセンサ列５Ａ〜５Ｄにおける磁気ラインセンサ５を複数本平行に配設するとともに、角度算出手段６は、平行に並ぶ各磁気ラインセンサ（各磁気ラインセンサ列５Ａ〜５Ｄ）の同じ長さ方向位置の磁気センサ素子５ａの検出値を平均又は加算する平行部出力処理部と、該平行部出力処理部によって平均又は加算された値から磁気発生手段３の回転角度を算出する角度算出部とを有している（いずれも不図示）。尚、上記磁気ラインセンサ列５Ａ〜５Ｄが成す矩形の中心は、回転側部材１の回転軸ｍと一致させているとともに、その他の構成については、第１の実施形態と同様である。
【００５４】
上記平行部出力処理部は、平行に並ぶ複数の磁気ラインセンサ列５Ａ〜５Ｄのそれぞれに設けられるものであり、本実施形態においては、各辺において４本の磁気ラインセンサ列５Ａ〜５Ｄがそれぞれ平行に設けられているので、４個の平行部出力処理部が設けられる。かかる構成においては、図１０に示すように、平行に並ぶ各磁気ラインセンサ（各磁気ラインセンサ列５Ａ〜５Ｄ）の同じ長さ方向位置の磁気センサ素子５ａの検出値を平行部出力処理部にて平均又は加算してＳ（ｘ）を求め、それを位置ｘにおける値とする。
【００５５】
上記のように、平行部出力処理部によって平均又は加算された値Ｓ（ｘ）に基づいて角度算出部によって磁気発生手段３の回転角度を算出する。本実施形態においては、各磁気ラインセンサ５Ａ〜５Ｄにおいて４本のラインセンサが配設されているので、各素子５ａのばらつき及びノイズは約１／２に減少することとなる。これは、センサ数Ｎとノイズ量との関係が、正規分布になる現象の場合、ノイズ量＝１／√Ｎとなることが知られているからである。
【００５６】
よって、先に説明した他の実施形態と同様、磁気ラインセンサ５で検出された出力に伴う各素子５ａの特性又は付随する回路のばらつき、或いはノイズの影響を低減しつつ（影響されず）磁気発生手段３の回転角度を検出することができるので、ばらつきやノイズを除去すべく別途の情報処理工程（例えば空間フィルタによるノイズ除去工程等）が不要となり、回転角度の算出をより素早く且つ正確に行うことができる。
【００５７】
次に、本発明に係る第４の実施形態について説明する。
本実施形態に係る回転検出装置は、第１の実施形態と同様、回転側部材１に配設された磁気発生手段３の回転角度を検出するためのもので、角度算出手段にて磁界分布のゼロクロスを検出して磁気発生手段３の回転角度を計算するよう構成されている。具体的には、図１１に示すように、ゼロクロス位置近傍（同図中符号αで示した範囲）の候補となるデータに対する直線（ｙ＝ａｘ＋ｂ）の最小自乗近似を求めてゼロクロス（同図中符号Ｚで示した位置）を求めるよう構成されている。
【００５８】
上記最小自乗近似の処理は、各磁気ラインセンサ列５Ａ〜５Ｄについてそれぞれ行うものとし、その演算方法は以下の如くである。まず、既述のようにαで示したゼロクロス位置近傍の候補の出力データを抽出し、仮定した直線と実際に検出された出力データの差の２乗和を評価値とし、該評価値が最小となるような直線を求める（最小自乗法）。
【００５９】
例えば、ｙ＝ａｘ＋ｂなる直線を仮定し、ある位置ｘにおける出力データｓｉとの差ｅｉ＝ｙ−ｓｉの２乗を加算した値Ｅを以下の如く求める。
【００６０】
【数１２】

【００６１】
上記Ｅを評価値として、これが最小になるときのａ、ｂ（仮定した直線ｙ＝ａｘ＋ｂの定数）を求める。即ち、評価値Ｅをａ、ｂで微分した値が０となる条件を求めると、抽出された出力データの個数をＮとした場合、以下の如き演算にて求められる。
【００６２】
【数１３】

【００６３】
上記の如く求まったａ、ｂにて直線の式が決定され、該直線の式からｙ＝０となるときのｘ、即ちｘ＝−ｂ／ａなる演算にてゼロクロス位置の座標を求めることができる。求まった２つのゼロクロス位置が、例えば図１２の如き位置である場合、同図中の寸法Ａ及びＢを用いて以下の演算を行えば２つのゼロクロスを結んだ直線の角度が求まる。これが磁気発生手段３の回転角度となる。
【００６４】
【数１４】

【００６５】
尚、４つの磁気ラインセンサ列５Ａ〜５Ｄが成す矩形の４隅部分に磁界の境界線が存在し、２つ以上の磁気ラインセンサ列でゼロクロスが求まった場合、演算に使用した点数の多い列のデータを採用する、又は隣接する磁気ラインセンサ列間の平均をとるなどの処理を行い、角度計算に使用する座標を決定するようにするのが好ましい。
【００６６】
本実施形態によれば、最小自乗法により近似直線を求めており、該最小自乗法による演算は統計量の計算となるため、第１〜第３の実施形態と同様、磁気ラインセンサ５で検出された出力に伴う各素子５ａの特性又は付随する回路のばらつき、或いはノイズの影響を低減しつつ（影響されず）磁気発生手段３の回転角度を検出することができる。
【００６７】
次に、本発明に係る第５の実施形態について説明する。
本実施形態に係る回転検出装置は、第１の実施形態と同様、回転側部材１に配設された磁気発生手段３の回転角度を検出するためのもので、第４の実施形態と同様、角度算出手段にて磁界分布のゼロクロスを検出して磁気発生手段３の回転角度を計算するよう構成されている。本実施形態においては、角度算出手段にて、磁気ラインセンサ５の出力と基準波形との差分の和を規定のデータ個数に基づいて計算し、その値が最小となる位相を求め、該位相よりゼロクロスを求めるよう構成されている。
【００６８】
具体的には、基準波形として、例えば図１３に示すような符号関数、又は図１４に示すような１次関数を予め定義しておく。即ち、図１３で示す基準波形（符号関数）は、
Ｐ（ｘ）＝＋１（ｘ＞０）
０（ｘ＝０）
−１（ｘ＜０）
と定義され、図１４で示す基準波形（直線）は、Ｐ（ｘ）＝ｘと定義される。
【００６９】
そして、例えばｉ番目の素子５ａの出力Ｓ（ｉ）に関して、前後Ｎ個ずつのデータを参照して、基準波形との差分の絶対値を加算した値Ｄ（ｉ）を角度算出手段にて算出する。かかる差分の絶対値の和Ｄの算出は以下の通りである。
【００７０】
【数１５】

【００７１】
然るに、対象とするセンサ番号ｉを順次ずらしていき、それぞれの位置における差分の絶対値の和Ｄ（ｉ）を求め、各位置（位相）で計算した差分の和Ｄ（ｉ）をプロットすると、図１５で示したような曲線Ｄ（ｉ）が得られる。かかる曲線Ｄ（ｉ）のうち最小となるセンサ番号がゼロクロス位置となる。例えば、差分値Ｄ（ｉ）の最小値付近を２次関数などでフィッティングして、最小位置を小数点以下まで予測することにより、ゼロクロス位置を精度よく求めることができる。
【００７２】
尚、図１５で示した曲線Ｄ（ｉ）では、２つのゼロクロスのうち一方のみが検出されるので、基準波形Ｐ（ｘ）（図１３で示す符号関数及び図１４で示す直線）の符号を反転して上記と同様の演算を行えば、他方のゼロクロスをも検出することができる。
【００７３】
次に、本発明に係る第６の実施形態について説明する。
本実施形態に係る回転検出装置は、第１の実施形態と同様、回転側部材１に配設された磁気発生手段３の回転角度を検出するためのもので、第４及び第５の実施形態と同様、角度算出手段にて磁界分布のゼロクロスを検出して磁気発生手段３の回転角度を計算するよう構成されている。本実施形態においては、角度算出手段にて、磁気ラインセンサ５の出力と基準波形との相関値を規定のデータ個数に基づいて計算し、その値が最大及び最小となる位相をそれぞれ求め、これら位相によりゼロクロスを求めるよう構成されている。
【００７４】
具体的には、第５の実施形態と同様、基準波形として、例えば図１３に示すような符号関数、又は図１４に示すような１次関数を予め定義しておく。そして、例えばｉ番目の素子５ａの出力Ｓ（ｉ）に関して、前後Ｎ個ずつのデータを参照して、基準波形との相関値Ｃ（ｉ）を角度算出手段にて算出する。かかる相関値Ｃの算出は以下の通りである。
【００７５】
【数１６】

【００７６】
然るに、対象とするセンサ番号ｉを順次ずらしていき、それぞれの位置における相関値Ｃ（ｉ）を求め、各位置（位相）で計算した相関値Ｃ（ｉ）をプロットすると、図１６で示したような曲線Ｃ（ｉ）が得られる。かかる曲線Ｃ（ｉ）のうち最大及び最小となるセンサ番号がゼロクロス位置となる。例えば、相関値Ｃ（ｉ）の極値付近を２次関数などでフィッティングして、最大及び最小位置を小数点以下まで予測することにより、ゼロクロス位置を精度よく求めることができる。尚、基準波形を１（一定値）とした場合には、相関値Ｃ（ｉ）は磁気ラインセンサ５の出力波形Ｓ（ｉ）の移動平均値となる。即ち、出力波形Ｓ（ｉ）のノイズを除去した波形を得ることができるので、Ｃ（ｉ）が０となる位相を求めれば、その位相がゼロクロス位置となるのである。
【００７７】
次に、その他の実施形態について説明する。
例えば、第２の実施形態の如く重心まわりのモーメント計算を実施する場合、磁気発生手段３の回転角度方向に磁気ラインセンサ５を構成する素子５ａが等密度で分布している必要がある。かかる素子５ａが等密度で分布していないと、当該密度そのものがモーメントを持ってしまうこととなり、角度検出精度に影響を与えてしまうからである。
【００７８】
ここで、第２実施形態に係る回転検出装置において、矩形状を成す磁気ラインセンサ列５Ａ〜５Ｄの４隅に当該矩形状の内部と外部との配線のための不連続な部分が存在しているため、重心まわりのモーメント計算をそのまま実施すると、図１７に示すような不連続な部分による不均一な素子５ａの配置密度の影響によって、実際の磁気発生手段３の回転角度との誤差が局所的に大きくなる傾向がある。また、回転中心から見た隣接する素子５ａの角度差が異なることによっても、配置密度に影響を生じることとなり、誤差を大きくしてしまう要因になってしまう。
【００７９】
よって、精度良く角度検出を行うためには、上記の如く局所的に生じる大きな誤差及び回転中心から見た隣接する素子５ａの角度の違いによる誤差を補正する必要がある。例えば、実際の磁気ラインセンサ５の配置によって決まる情報から、配置密度が角度検出に及ぼす影響を予め計算しておき、角度検出のための演算を実行する際に補正を加えることにより、より高精度な角度検出のための演算を可能にすることができる。
【００８０】
具体的には、回転中心から見たｉ番目の素子５ａと（ｉ＋１）番目の角度がそれぞれθ（ｉ）及びθ（ｉ＋１）で、角度差ｄθ＝θ（ｉ）−θ（ｉ＋１）であるとき、ｉ番目の出力データεｉ（図６（ｃ）参照）にはＡ（ｄθ）の重みを掛けることにより、Ａ（ｄθ）εｉを出力データとして扱うこととする。かかる重み付けは、次の素子５ａとの角度差を元に行ってもよいし、前後の素子５ａの個数の角度差を元に行ってもよい。
【００８１】
一方、図１７で示すような磁気ラインセンサ列５Ａ〜５Ｄ間の不連続な部分によって局所的に生じる大きな誤差を補正するには、その部分（磁気ラインセンサ５の４隅部分）に補正を加えるためのテーブルを予め用意しておき、当該誤差を抑制するのが好ましい。即ち、磁気ラインセンサ５の４隅部分がゼロクロス位置となる４５度、１３５度、２２５度及び３１５度付近で素子５ａの不連続性に基づく局所的な大きな誤差が生じるので、かかる部位に補正係数を掛けて重みを付与し、角度検出誤差を抑制するものである。
【００８２】
要するに、磁界強度のゼロクロス近傍の出力を抽出し、その出力がゼロに近いほど値が大きくなるようにデータ変換して重心まわりのモーメント計算を行うことにより磁気発生手段３の回転角度を算出するものにおいて、磁気ラインセンサ５における素子５ａの角度方向配置密度を元に補正値を計算し、出力データに補正のための重みを付与することにより、当該配置密度の不均一性に起因する角度検出誤差を低減するのである。
【００８３】
上記の如く誤差を小さくした出力データに基づきモーメント計算を施すようにすれば、磁気ラインセンサ５の４隅部分における素子５ａの不連続な部分であっても、回転角度の算出への悪影響を最小限に抑えることができる。尚、このように、磁気ラインセンサ５の４隅部分に相当する極端に大きな補正係数をテーブル化して当該部分の出力データに対する重みを付与するようにすれば、その都度演算処理を施す場合に比べ、出力データを処理するための角度算出手段６の容量を小さくすることができ、装置全体を小型化することができる。
【００８４】
以上、本実施形態に係る回転検出装置について説明したが、上記の如き磁気発生手段が配設された回転側部材を転がり軸受等の回転輪とし、静止輪から当該磁気発生手段と対向する部位まで板材等を延設させ、これを固定側部材とすることにより、上記構成要素を持った回転検出装置付き軸受としてもよい。かかる構成によれば、軸受のサイズが小さい小径軸受にも回転検出装置を容易に内蔵させることができる。また、軸受に回転検出装置を配設して、これらを一体構成することができるので、当該軸受の部品点数、組立工数の削減、及び小型化を図ることができる。
【００８５】
また、角度算出手段により求められた回転角度の算出結果をパルス変換して、そのパルス信号を出力するよう構成してもよい。かかる構成によれば、回転角度出力としてインクリメンタルな信号を出力することができる。更に、角度算出手段による算出結果に基づく情報を無線で送信し得る送信手段を具備するようにしてもよい。この送信手段を具備することにより、出力ケーブルなしで信号を取り出すことができ、当該出力ケーブルの敷設作業を不要とすることができる。尚、送信手段はワイヤレスであれば足り、無線電波、光信号その他の信号送信手段とすることができる。然るに、当該送信手段を磁気ラインセンサに隣接して設けるようにすれば、送信機能付きの小型の回転検出装置を提供することができる。
【００８６】
更に、第３実施形態の如く磁気ラインセンサを複数本平行に並べて配設するとともに、これら平行に並ぶ各磁気ラインセンサの同じ長さ方向位置の磁気センサ素子の検出値を平均又は加算しておき、その平均又は加算された値に基づいて、第１実施形態の如くフーリエ変換による基本波の位相を求め、回転角度を算出したり、或いは第２実施形態の如く重心まわりのモーメント計算を行って回転角度を算出したりすることができる。これら方法（第１実施形態と第３実施形態との組み合わせ、及び第２実施形態と第３実施形態との組み合わせ）によれば、磁気ラインセンサによる出力波を整えた後、各演算を行うことができるので、より精度よく回転角度の算出を行うことができる。
【００８７】
【発明の効果】
請求項１の発明によれば、角度算出手段が磁気ラインセンサで検出された出力に伴う各素子特性又は付随する回路のばらつき、或いはノイズの影響を低減しつつ磁気発生手段の回転角度を算出し得るので、これらばらつきやノイズを除去すべく別途の情報処理工程が不要となり、小型の機器への組み込み、及び高精度な回転角度の検出を可能とするとともに、回転角度の算出をより素早く且つ正確に行うことができる。
【００８８】
請求項２の発明によれば、平行部出力処理部にて平行に並ぶ各磁気ラインセンサの同じ長さ方向位置の磁気センサ素子の検出値を平均又は加算するとともに、角度算出部にて平行部出力処理部によって平均又は加算された値から磁気発生手段の回転角度を算出するので、更に精度よく回転角度の検出を可能とすることができる。
【００８９】
請求項３の発明によれば、基本波位相演算部にて磁気ラインセンサ全体の出力をまとめてフーリエ変換の演算を行い基本波の位相を求めるとともに、角度算出部にて基本波位相演算部により求められた基本波の位相から磁気発生手段の角度を算出するので、更に回転角度の算出を素早く且つ正確に行うことができるとともに、磁気ラインセンサが不連続に配置されている場合でも対応可能である。
【００９０】
請求項４の発明によれば、重み付与部にて磁気ラインセンサの検出値を磁界分布のゼロ付近で最も大きくなるように、且つ、ゼロから離れた位置では殆ど検出値がないように変換することにより、ゼロ付近に重みを持ったデータ列が作られるとともに、角度算出部にて当該データ列に基づいて２次元座標を用いた重心まわりのモーメント計算を行って磁気発生手段の回転角度を算出するので、更に回転角度の算出を素早く且つ正確に行うことができる。
【００９１】
請求項５〜請求項７の発明によれば、データに対する直線の最小自乗近似、出力と基準波形との差分の和、又は出力と基準波形との相関値によりそれぞれゼロクロス位置を求めるので、検出される角度位置の更なる精度向上を図ることができる。
【００９２】
請求項８の発明によれば、角度算出手段が回転角度の算出結果をパルス変換して、そのパルス信号を出力するものであるので、回転角度出力としてインクリメンタルな信号を出力することができる。
【００９３】
請求項９の発明によれば、送信手段にて角度算出手段による算出結果に基づく情報を無線で送信するので、出力ケーブル無しで信号を取り出すことができ、当該出力ケーブルの敷設作業を不要とすることができる。
【００９４】
請求項１０の発明によれば、軸受に回転検出装置を配設して、これらを一体構成することができ、当該軸受の部品点数、組立工数の削減、及び小型化を図ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係る回転検出装置を示す模式図
【図２】同回転検出装置における磁気ラインセンサ及び角度算出手段を示す模式図
【図３】同回転検出装置における磁気ラインセンサ及び角度算出手段を示すブロック図
【図４】同回転検出装置における磁気ラインセンサからの出力を示すグラフ
【図５】本発明の第２の実施形態に係る回転検出装置における磁気ラインセンサ及び角度算出手段を示すブロック図
【図６】同回転検出装置における角度算出手段での処理手順を示す説明図であって、（ａ）磁気ラインセンサからの出力波形Ｓｉを示す図（ｂ）所定演算を施した後の出力波形ｆｉを示す図（ｃ）更に所定処理を施した後の出力波形εｉを示す図
【図７】同回転検出装置における角度算出手段により画像処理した出力例の画面を示す図
【図８】図７の出力の画面に基づいた情報により得られる直線配置の説明図
【図９】本発明の第３の実施形態に係る回転検出装置における複数平行に配設された磁気ラインセンサを示す説明図
【図１０】同回転検出装置における磁気ラインセンサの出力処理の説明図
【図１１】本発明の第４の実施形態に係る回転検出装置における磁気ラインセンサからの出力波形及び仮定の直線を示す模式図
【図１２】同回転検出装置における磁気ラインセンサのゼロクロス位置を示す模式図
【図１３】本発明の第５の実施形態に係る回転検出装置の処理過程で使用される基準波形（符号関数）を示す図（第６の実施形態において使用するものも同様）
【図１４】同回転検出装置の処理過程で使用される基準波形（直線）を示す図（第６の実施形態において使用するものも同様）
【図１５】同回転検出装置における磁気ラインセンサからの出力波形及び処理後の波形Ｄ（ｉ）を示すグラフ
【図１６】本発明の第６の実施形態に係る回転検出装置における磁気ラインセンサからの出力波形及び処理後の波形Ｃ（ｉ）を示すグラフ
【図１７】本発明の他の実施形態における磁気ラインセンサからの出力波形（処理前の状態）を示すグラフ
【符号の説明】
１…回転側部材
２…非回転側部材
３…磁気発生手段
４…半導体チップ
５…磁気ラインセンサ
５Ａ〜５Ｄ…磁気ラインセンサ列
５ａ…素子
６…角度算出手段
７…基本波位相演算部
８…角度算出部
９…重み付与部
１０…角度算出部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation detection device that performs rotation detection for rotation control of a small motor, for example, and a bearing with a rotation detection device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, a magnetic bearing is fixed to a rotating wheel of a rolling bearing, and a magnetic sensor such as a Hall element is disposed on a stationary ring, so that a rolling sensor is built in the rolling bearing. However, in such a rotation detection device, when applied to a small-diameter bearing with a small size of the rolling bearing, it is difficult to accommodate the magnetic sensor within the outer diameter of the stationary ring, and the number of rotation pulses per rotation is 500 or more. It has a drawback that it is difficult to detect a rotation angle with high accuracy that can be secured.
[0003]
In order to eliminate the above-mentioned drawbacks, for example, as shown in Patent Document 1, a magnetic generating means protrudes from the rotating wheel in the direction of the rotation axis, and a magnetic sensor element is arrayed at a position facing the magnetic generating means in the stationary wheel. There has been proposed a configuration in which a rotation angle and a rotation direction of magnetism generating means (that is, a rotating wheel) are detected from information on a magnetic field distribution detected by the magnetic sensor element. According to such a rotation detection device, the rotation detection device can be easily incorporated in a small diameter bearing having a small size of the rolling bearing.
[0004]
[Patent Document 1]
JP 2003-148999 A
[0005]
[Problems to be solved by the invention]
However, in the above conventional rotation detection device, the magnetic distribution information detected by the magnetic sensor element is affected by each element characteristic or the accompanying circuit variation or noise, and such information variation or noise is removed. A separate information processing step is required. Therefore, there is a problem that it takes time to calculate the rotation angle of the magnetism generating means based on the magnetic distribution information detected by the magnetic sensor element.
[0006]
The present invention has been made in view of such circumstances, and enables incorporation into a small device and detection of a highly accurate rotation angle, and calculation of the rotation angle more quickly and accurately. An object of the present invention is to provide a rotation detection device and a bearing with a rotation detection device.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is arranged on the rotating side member, and is arranged on the non-rotating side member facing the magnetism generating means and the magnetism generating means for generating anisotropic magnetism in the circumferential direction around the center of rotation. A rotation detection device comprising: a magnetic line sensor for detecting magnetism of the magnetic generation means; and an angle calculation means for calculating a rotation angle of the magnetic generation means from an output detected by the magnetic line sensor, The magnetic line sensor is arranged side by side around the center of rotation of the magnetism generating means, and the angle calculating means is configured such that each element characteristic accompanying the output detected by the magnetic line sensor or an accompanying circuit variation, Alternatively, the rotation angle of the magnetism generating means can be calculated while reducing the influence of noise.
[0008]
According to a second aspect of the present invention, in the rotation detecting device according to the first aspect, a plurality of the magnetic line sensors are arranged in parallel and the angle calculation means has the same length of each of the magnetic line sensors arranged in parallel. A parallel part output processing unit that averages or adds the detection values of the magnetic sensor elements at the vertical position, and an angle calculation unit that calculates the rotation angle of the magnetism generating unit from the value averaged or added by the parallel part output processing unit; It is characterized by having.
[0009]
According to a third aspect of the present invention, in the rotation detection device according to the first or second aspect, the angle calculation means collects the output of the entire magnetic line sensor and performs a Fourier transform operation to calculate the phase of the fundamental wave. A fundamental wave phase calculation unit that calculates the angle, and an angle calculation unit that calculates the angle of the magnetism generating means from the phase of the fundamental wave calculated by the fundamental wave phase calculation unit.
[0010]
According to a fourth aspect of the present invention, in the rotation detection device according to the first or second aspect, the angle calculation unit is configured so that the detection value of the magnetic line sensor is maximized near zero of the magnetic field distribution, and By converting so that there is almost no detection value at a position away from zero, a weighting unit that creates a data string having a weight near zero, and a two-dimensional coordinate based on the data string created by the weighting unit And an angle calculating unit for calculating a rotation angle of the magnetism generating means by calculating a moment around the center of gravity using the.
[0011]
According to a fifth aspect of the present invention, in the rotation detection device according to the first aspect, the angle calculation means detects a zero cross of a magnetic field distribution and calculates a rotation angle of the magnetic generation means. Further, it is obtained by using a least square approximation of a straight line with respect to candidate data in the vicinity of the zero cross position in the output of the magnetic line sensor.
[0012]
According to a sixth aspect of the present invention, in the rotation detection device according to the first aspect, the angle calculation means detects a zero cross of a magnetic field distribution and calculates a rotation angle of the magnetic generation means. The sum of the difference between the output of the sensor and the reference waveform is calculated based on the prescribed number of data, the phase having the minimum value is obtained, and the zero cross is obtained from the phase.
[0013]
According to a seventh aspect of the present invention, in the rotation detection device according to the first aspect, the angle calculation means detects a zero cross of a magnetic field distribution and calculates a rotation angle of the magnetic generation means, and the magnetic line The correlation value between the output of the sensor and the reference waveform is calculated based on the prescribed number of data, the phase at which the value is maximum and minimum is determined, and the zero cross is determined by the phase.
[0014]
According to an eighth aspect of the present invention, in the rotation detection device according to any one of the first to seventh aspects, the angle calculation means performs pulse conversion on the calculation result of the rotation angle and outputs the pulse signal. It is a thing to do.
[0015]
A ninth aspect of the present invention is the rotation detection device according to any one of the first to eighth aspects, further comprising a transmission unit capable of wirelessly transmitting information based on a calculation result by the angle calculation unit. It is characterized by.
[0016]
A tenth aspect of the present invention is a bearing with a rotation detection device incorporating the rotation detection device according to any one of the first to ninth aspects.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
A rotation detection device according to an embodiment of the present invention is for detecting a rotation angle with respect to a member fixed on a non-rotation side (fixed side) in a rotation side member rotatable around a predetermined axis, As shown in FIG. 1, it has a rotating side member 1 that is rotatable about an axis m, and a magnetic generating means 3 that is disposed on the rotating side member 1 and rotates with the rotation of the rotating side member 1. Yes.
[0018]
The magnetism generating means 3 generates anisotropic magnetism in the circumferential direction around the rotation center (around the axis m), and as shown in the figure, a permanent magnet 3a and both end faces of the permanent magnet 3a It is comprised from the magnetic bodies 3b and 3c extended from. That is, the magnetism generating means 3 is generally U-shaped as a whole, and magnetism occurs such that one protruding end (for example, the tip of the magnetic body 3b) has an S pole and the other protruding end (for example, the tip of the magnetic body 3c) has an N pole. ing.
[0019]
On the other hand, as shown in the figure, a semiconductor chip 4 made of, for example, a silicon chip is fixed on the non-rotating side member 2 at a position facing the magnetism generating means 3, and the surface of the semiconductor chip 4 (magnetic A magnetic line sensor 5 and an angle calculating means 6 made of, for example, an integrated circuit are formed on the surface facing the generating means 3. There is a slight clearance between the magnetic line sensor 5 and the angle calculating means 6 on the semiconductor chip 4 and the projecting ends of the magnetism generating means 3 (tips of the magnetic bodies 3b and 3c), and both members interfere with each other. It is configured not to.
[0020]
More specifically, as shown in FIG. 2, the magnetic line sensor 5 includes elements 5a that can detect magnetism arranged in a line (straight), and includes four magnetic line sensor arrays 5A. Are arranged in a rectangular shape around the rotation center of the magnetism generating means 3, and the angle calculating means 6 is formed in a portion surrounded by the magnetic line sensor rows 5A to 5D. . By setting it as such a structure, the magnetic line sensor 5 and the angle calculation means 6 can be arrange | positioned compactly, and size reduction of the whole apparatus can be achieved.
[0021]
The angle calculating means 6 is for calculating the rotation angle of the magnetism generating means 3 from the output detected by the magnetic line sensor 5, and as shown in FIG. The fundamental wave phase calculation unit 7 that obtains the phase of the fundamental wave by performing a Fourier transform operation by combining all outputs including all of 5D, and the phase of the fundamental wave obtained by the fundamental wave phase calculation unit 7 An angle calculator 8 for calculating the angle of the magnetism generating means 3.
[0022]
In the magnetic line sensor 5 according to the present embodiment, since it is necessary to pass wiring between the inner side and the outer side surrounded by the arrangement, as shown in FIG. 2, between the magnetic line sensor rows 5 </ b> A to 5 </ b> D on each side. In this state, a discontinuous waveform as shown in FIG. 4 can be obtained as an output from the magnetic line sensor 5. The discontinuous waveform is obtained by sequentially assigning numbers to the elements 5a constituting the magnetic line sensor 5, and plotting the elements on the horizontal axis and the outputs of the respective elements 5a on the vertical axis. It is a thing.
[0023]
Hereinafter, with respect to the calculation method of the Fourier transform for the discontinuous waveform, the calculation contents when the output of each element 5a is Sn, the number of elements N, and the fundamental wave φ are shown below.
[0024]
[Expression 1]

[0025]
Here, if the physical arrangement of the element 5a in the magnetic line sensor 5 is known, the relationship of the physical angle Θ of the magnetic generating means 3 is obtained by a predetermined calculation based on the phase φ of the fundamental wave obtained by the above calculation. Can do. For example, in the angle calculation unit 8, if the correspondence relationship between the phase φ obtained by the fundamental phase calculation unit 7 and the physical angle Θ of the magnetic generation unit 3 is stored as a conversion table, the rotation of the magnetic generation unit 3 is stored. The angle can be easily obtained.
[0026]
As shown in the above calculation contents, according to the method using the Fourier transform calculation method, the coordinate value of each sensor element 5a is not used, so that the angle calculation means 6 that is a processing circuit can have a simple configuration. In other words, the rotation angle of the magnetism generating means 3 is detected while reducing (not affected by) the influence of the characteristics of each element 5a or the accompanying circuit variations accompanying the output detected by the magnetic line sensor 5 or noise. Therefore, a separate information processing step (for example, a noise removal step using a spatial filter) is not required to remove variations and noise, and the rotation angle can be calculated more quickly and accurately.
[0027]
Next, a second embodiment according to the present invention will be described.
As in the first embodiment, the rotation detection device according to the present embodiment is for detecting the rotation angle of the magnetism generating means 3 disposed on the rotation-side member 1, and as shown in FIG. The line sensor 5 is composed of magnetic line sensor rows 5A to 5D arranged in a rectangular shape, and an angle calculating means 6 is formed in a portion surrounded by them.
[0028]
Here, as shown in FIG. 5, the angle calculation means 6 in the present embodiment is such that the detection value of the magnetic line sensor is maximized in the vicinity of zero of the magnetic field distribution and is almost at the position away from zero. By converting so that there is no weight, a weighting unit 9 for creating a data string having a weight near zero, and a moment around the center of gravity using a two-dimensional coordinate based on the data string created by the weighting unit 9 And an angle calculation unit 10 that calculates the rotation angle of the magnetism generating means 3.
[0029]
For example, it is possible to use a center-of-gravity / spindle calculation method used for measurement in an image mainly in image processing. That is, the angle calculation means 6 in this embodiment uses such a center-of-gravity / spindle calculation method, and basically calculates the moment of inertia by considering the data as mass by the least square error method. The angle calculation is performed as follows. Specifically, the following calculation is performed.
[0030]
First, an average value of sensor outputs is obtained by the following calculation, and this is set as a zero value (see FIG. 6A). The output of each element 5a is Si, the number of data is N, and the zero value is Save.
[0031]
[Expression 2]

[0032]
Next, the following calculation for conversion is performed so that the closer to the average value (zero value), the larger the value becomes (see FIG. 5B).
[0033]
[Equation 3]

[0034]
Then, for example, the conversion value or the fixed value is subtracted, and when it becomes a negative value, it is set to 0. For example, data far from the average value (zero value) is converted to a value as small as possible (see (c) in the figure).
[0035]
[Expression 4]

[0036]
As a result of the above data conversion, a data string having a weight as the sensor output close to the zero line mainly becomes closer to the zero line is formed. When an operation is performed on the data string, which will be described later, a rotation angle can be detected as shown in FIG.
[0037]
That is, when the straight line detected in the figure is defined with the orientation information, as shown in FIG. 8, the straight line can be represented by the angle Θ and the distance f from the origin, and the unit vector e of the straight line direction _i , The unit vector orthogonal to it _f Then,
e _i = (Cosθ, sinθ)
e _f = (− Sinθ, cosθ)
The straight line is fe with λ being an arbitrary value. _f + Λe _i And the distance between the straight line and the point P (x, y) is

It can be expressed as.
[0038]
When the data of the point P (x, y) is mi, the amount of deviation from the straight line is calculated as follows and used as the evaluation value. Such an evaluation value is equivalent to the above-described sum of square errors or moment calculation about the axis.
[0039]
[Equation 5]

[0040]
The evaluation value I is a function of Θ and f, and takes an extreme value when the moment becomes a maximum or minimum straight line through the center of gravity. And
[0041]
[Formula 6]

[0042]
The following conditions are obtained.
[0043]
[Expression 7]

[0044]
Here, each symbol in the arithmetic expression indicates the following contents.
[0045]
[Equation 8]

[0046]
Further, A, B and C are defined as follows.
[0047]
[Equation 9]

[0048]
From A, B, and C defined as above, the rotation angle can be obtained as follows.
[0049]
[Expression 10]

[0050]
When the conditions are specified and summarized, the following results are obtained.
[0051]
[Expression 11]

[0052]
According to this embodiment, since the rotation angle of the magnetism generating means 3 is basically calculated by statistical calculation, it is not easily affected by variations in the element 5a or noise, and is processed as two-dimensional data. It is also possible to avoid an adverse effect caused by the displacement between the generating means 3 and the element 5a of the magnetic line sensor 5.
[0053]
Next, a third embodiment according to the present invention will be described.
As in the first embodiment, the rotation detection device according to the present embodiment is for detecting the rotation angle of the magnetism generating means 3 disposed on the rotation side member 1, and as shown in FIG. A plurality of the magnetic line sensors 5 in the magnetic line sensor rows 5A to 5D are arranged in parallel, and the angle calculation means 6 has the same length direction of the magnetic line sensors arranged in parallel (each magnetic line sensor row 5A to 5D). A parallel part output processing unit that averages or adds the detection values of the magnetic sensor elements 5a at the position, and an angle calculation unit that calculates the rotation angle of the magnetism generating means 3 from the value averaged or added by the parallel part output processing unit. It has (all are not shown). The center of the rectangle formed by the magnetic line sensor rows 5A to 5D coincides with the rotation axis m of the rotation side member 1, and the other configurations are the same as those in the first embodiment.
[0054]
The parallel part output processing unit is provided in each of the plurality of magnetic line sensor arrays 5A to 5D arranged in parallel. In the present embodiment, four magnetic line sensor arrays 5A to 5D are provided on each side. Since they are provided in parallel, four parallel part output processing units are provided. In such a configuration, as shown in FIG. 10, the detection values of the magnetic sensor elements 5a at the same length direction position of the magnetic line sensors arranged in parallel (each magnetic line sensor row 5A to 5D) are sent to the parallel output processing unit. And average or add to obtain S (x), which is the value at position x.
[0055]
As described above, the rotation angle of the magnetism generating unit 3 is calculated by the angle calculation unit based on the value S (x) averaged or added by the parallel unit output processing unit. In the present embodiment, since four line sensors are arranged in each of the magnetic line sensors 5A to 5D, the variation and noise of each element 5a are reduced to about ½. This is because it is known that the noise amount = 1 / √N in the case of a phenomenon in which the relationship between the number of sensors N and the noise amount is a normal distribution.
[0056]
Therefore, as in the other embodiments described above, the magnetic property of each element 5a accompanying the output detected by the magnetic line sensor 5 or the accompanying circuit variation, or the influence of noise is reduced (not affected). Since the rotation angle of the generating means 3 can be detected, a separate information processing step (for example, a noise removal step using a spatial filter) is not required to remove variations and noise, and the rotation angle can be calculated more quickly and accurately. It can be carried out.
[0057]
Next, a fourth embodiment according to the present invention will be described.
As in the first embodiment, the rotation detection device according to the present embodiment is for detecting the rotation angle of the magnetism generating means 3 disposed on the rotation side member 1, and the angle calculation means detects the magnetic field distribution. The zero cross is detected and the rotation angle of the magnetism generating means 3 is calculated. Specifically, as shown in FIG. 11, a least-square approximation of a straight line (y = ax + b) is obtained for candidate data in the vicinity of the zero-cross position (the range indicated by the symbol α in the figure) to obtain a zero cross (in the figure). The position indicated by the symbol Z) is obtained.
[0058]
The least square approximation process is performed for each of the magnetic line sensor arrays 5A to 5D, and the calculation method is as follows. First, as described above, candidate output data in the vicinity of the zero crossing position indicated by α is extracted, and the sum of squares of the difference between the assumed straight line and the actually detected output data is used as an evaluation value, and the evaluation value is minimum. Find a straight line that gives (the least squares method).
[0059]
For example, assuming a straight line y = ax + b, a value E obtained by adding the square of the difference ei = y−si from the output data si at a certain position x is obtained as follows.
[0060]
[Expression 12]

[0061]
Using E as an evaluation value, a and b (assumed straight line y = ax + b constant) when this is minimized are obtained. That is, when a condition is obtained in which the value obtained by differentiating the evaluation value E with a and b is 0, when the number of extracted output data is N, it is obtained by the following calculation.
[0062]
[Formula 13]

[0063]
A straight line expression is determined by a and b obtained as described above, and x when y = 0 from the straight line expression, that is, the coordinates of the zero crossing position can be obtained by calculation of x = −b / a. it can. When the obtained two zero cross positions are positions as shown in FIG. 12, for example, the angle of a straight line connecting the two zero crosses can be obtained by performing the following calculation using the dimensions A and B in FIG. This is the rotation angle of the magnetism generating means 3.
[0064]
[Expression 14]

[0065]
If there are magnetic field boundaries at the four corners of the rectangle formed by the four magnetic line sensor rows 5A to 5D, and zero cross is obtained by two or more magnetic line sensor rows, the row having a large number of points used in the calculation It is preferable to determine the coordinates used for the angle calculation by adopting a process such as adopting the above data or taking an average between adjacent magnetic line sensor arrays.
[0066]
According to the present embodiment, an approximate straight line is obtained by the method of least squares, and the calculation by the method of least squares is a calculation of statistics, so that it is detected by the magnetic line sensor 5 as in the first to third embodiments. The rotation angle of the magnetism generating means 3 can be detected while reducing (not affected by) the influence of the characteristics of each element 5a or the accompanying circuit variation or noise caused by the outputted output.
[0067]
Next, a fifth embodiment according to the present invention will be described.
The rotation detection device according to the present embodiment is for detecting the rotation angle of the magnetism generating means 3 disposed on the rotation side member 1 as in the first embodiment, and as in the fourth embodiment, The angle calculating means detects the zero cross of the magnetic field distribution and calculates the rotation angle of the magnetism generating means 3. In the present embodiment, the angle calculation means calculates the sum of the differences between the output of the magnetic line sensor 5 and the reference waveform based on the prescribed number of data, obtains the phase that minimizes the value, and calculates the phase from the phase. It is configured to find the zero cross.
[0068]
Specifically, for example, a sign function as shown in FIG. 13 or a linear function as shown in FIG. 14 is defined in advance as the reference waveform. That is, the reference waveform (sign function) shown in FIG.
P (x) = + 1 (x> 0)
0 (x = 0)
-1 (x <0)
The reference waveform (straight line) shown in FIG. 14 is defined as P (x) = x.
[0069]
For example, with respect to the output S (i) of the i-th element 5a, the angle calculation means calculates a value D (i) obtained by adding the absolute value of the difference from the reference waveform with reference to N pieces of data before and after. To do. The calculation of the sum D of the absolute values of the differences is as follows.
[0070]
[Expression 15]

[0071]
However, when the target sensor number i is sequentially shifted, the sum D (i) of the absolute values of the differences at each position is obtained, and the sum of the differences D (i) calculated at each position (phase) is plotted. A curve D (i) as shown in FIG. 15 is obtained. The smallest sensor number in the curve D (i) is the zero cross position. For example, the zero cross position can be accurately obtained by fitting the vicinity of the minimum value of the difference value D (i) with a quadratic function or the like and predicting the minimum position to the decimal point.
[0072]
Since only one of the two zero crosses is detected in the curve D (i) shown in FIG. 15, the sign of the reference waveform P (x) (the sign function shown in FIG. 13 and the straight line shown in FIG. 14) is changed. If the same operation as described above is performed after inversion, the other zero cross can also be detected.
[0073]
Next, a sixth embodiment according to the present invention will be described.
As in the first embodiment, the rotation detection device according to the present embodiment is for detecting the rotation angle of the magnetism generating means 3 disposed on the rotation-side member 1, and the fourth and fifth embodiments. Similarly, the angle calculation means detects the zero cross of the magnetic field distribution and calculates the rotation angle of the magnetism generation means 3. In the present embodiment, the angle calculation means calculates the correlation value between the output of the magnetic line sensor 5 and the reference waveform based on the specified number of data, and obtains the phase at which the value is maximum and minimum, respectively. It is configured to obtain a zero cross according to the phase.
[0074]
Specifically, as in the fifth embodiment, as a reference waveform, for example, a sign function as shown in FIG. 13 or a linear function as shown in FIG. 14 is defined in advance. Then, for example, with respect to the output S (i) of the i-th element 5a, the angle calculation means calculates the correlation value C (i) with the reference waveform with reference to N pieces of data before and after. The calculation of the correlation value C is as follows.
[0075]
[Expression 16]

[0076]
However, the target sensor number i is sequentially shifted, the correlation value C (i) at each position is obtained, and the correlation value C (i) calculated at each position (phase) is plotted, as shown in FIG. A curve C (i) like this is obtained. The maximum and minimum sensor numbers in the curve C (i) are the zero cross positions. For example, the zero cross position can be obtained with high accuracy by fitting the vicinity of the extreme value of the correlation value C (i) with a quadratic function or the like and predicting the maximum and minimum positions to the decimal point. When the reference waveform is 1 (a constant value), the correlation value C (i) is a moving average value of the output waveform S (i) of the magnetic line sensor 5. That is, since the waveform from which the noise of the output waveform S (i) is removed can be obtained, if the phase where C (i) becomes 0 is obtained, the phase becomes the zero cross position.
[0077]
Next, other embodiments will be described.
For example, when the moment calculation around the center of gravity is performed as in the second embodiment, the elements 5 a constituting the magnetic line sensor 5 need to be distributed with equal density in the rotation angle direction of the magnetism generating means 3. This is because if the elements 5a are not distributed with equal density, the density itself has a moment, which affects the angle detection accuracy.
[0078]
Here, in the rotation detection device according to the second embodiment, there are discontinuous portions for wiring between the inside and outside of the rectangular shape at the four corners of the magnetic line sensor rows 5A to 5D having the rectangular shape. Therefore, if the moment calculation around the center of gravity is performed as it is, an error from the actual rotation angle of the magnetism generating means 3 is locally caused by the influence of the non-uniform arrangement density of the elements 5a due to the discontinuous portions as shown in FIG. Tend to be large. In addition, even if the angle difference between the adjacent elements 5a as viewed from the center of rotation is different, the arrangement density is affected, which increases the error.
[0079]
Therefore, in order to perform angle detection with high accuracy, it is necessary to correct a large error that occurs locally as described above and an error due to an angle difference between adjacent elements 5a viewed from the rotation center. For example, from the information determined by the actual arrangement of the magnetic line sensor 5, the influence of the arrangement density on the angle detection is calculated in advance, and correction is performed when the calculation for the angle detection is performed. Calculation for accurate angle detection can be made possible.
[0080]
Specifically, the i-th element 5a and the (i + 1) -th angle viewed from the rotation center are θ (i) and θ (i + 1), respectively, and the angle difference dθ = θ (i) −θ (i + 1). At this time, by multiplying the i-th output data εi (see FIG. 6C) by the weight of A (dθ), A (dθ) εi is handled as output data. Such weighting may be performed based on the angle difference with the next element 5a, or may be performed based on the angle difference between the number of the preceding and following elements 5a.
[0081]
On the other hand, in order to correct a large error locally caused by a discontinuous portion between the magnetic line sensor rows 5A to 5D as shown in FIG. 17, correction is applied to that portion (four corner portions of the magnetic line sensor 5). It is preferable to prepare a table for this in advance to suppress the error. That is, since a large local error based on the discontinuity of the element 5a occurs in the vicinity of 45 degrees, 135 degrees, 225 degrees, and 315 degrees at which the four corners of the magnetic line sensor 5 are at the zero cross position, the correction coefficient is applied to such portions. To give a weight and suppress an angle detection error.
[0082]
In short, the rotation angle of the magnetic generating means 3 is calculated by extracting the output near the zero cross of the magnetic field strength, converting the data so that the value becomes larger as the output is closer to zero, and calculating the moment around the center of gravity. In this case, a correction value is calculated based on the angular direction arrangement density of the elements 5a in the magnetic line sensor 5, and a weight for correction is given to the output data, whereby an angle detection error caused by the non-uniformity of the arrangement density Is reduced.
[0083]
If the moment calculation is performed based on the output data with a reduced error as described above, even if the element 5a is discontinuous at the four corners of the magnetic line sensor 5, the adverse effect on the calculation of the rotation angle is minimized. To the limit. In this way, if an extremely large correction coefficient corresponding to the four corner portions of the magnetic line sensor 5 is tabulated and a weight is given to the output data of the portion, the calculation process is performed each time. The capacity of the angle calculation means 6 for processing output data can be reduced, and the entire apparatus can be reduced in size.
[0084]
As described above, the rotation detection device according to the present embodiment has been described. However, from the stationary wheel to a portion facing the magnetism generating means, the rotating side member provided with the magnetism generating means as described above is a rotating wheel such as a rolling bearing. It is good also as a bearing with a rotation detector with the said component by extending a board | plate material etc. and making this into a stationary-side member. According to such a configuration, the rotation detection device can be easily built in a small diameter bearing having a small bearing size. In addition, since the rotation detection device can be arranged on the bearing and integrated with each other, the number of parts of the bearing, the number of assembly steps can be reduced, and the size can be reduced.
[0085]
Further, the rotation angle calculation result obtained by the angle calculation means may be pulse-converted and the pulse signal may be output. According to this configuration, an incremental signal can be output as the rotation angle output. Furthermore, you may make it comprise the transmission means which can transmit the information based on the calculation result by an angle calculation means on radio. By providing this transmission means, a signal can be taken out without an output cable, and the laying operation of the output cable can be made unnecessary. The transmission means need only be wireless, and can be radio wave, optical signal or other signal transmission means. However, if the transmission means is provided adjacent to the magnetic line sensor, a small rotation detector with a transmission function can be provided.
[0086]
Furthermore, as in the third embodiment, a plurality of magnetic line sensors are arranged in parallel, and the detection values of the magnetic sensor elements at the same longitudinal direction position of the magnetic line sensors arranged in parallel are averaged or added. Based on the average or the added value, the phase of the fundamental wave by Fourier transform is obtained as in the first embodiment, the rotation angle is calculated, or the moment around the center of gravity is calculated as in the second embodiment. The rotation angle can be calculated. According to these methods (a combination of the first embodiment and the third embodiment, and a combination of the second embodiment and the third embodiment), each calculation is performed after adjusting the output wave from the magnetic line sensor. Therefore, the rotation angle can be calculated with higher accuracy.
[0087]
【The invention's effect】
According to the first aspect of the present invention, the angle calculation means calculates the rotation angle of the magnetism generation means while reducing the influence of each element characteristic or accompanying circuit variation or noise accompanying the output detected by the magnetic line sensor. This eliminates the need for a separate information processing step to eliminate these variations and noise, enables incorporation into a small device and detection of the rotation angle with high accuracy, and enables calculation of the rotation angle more quickly and accurately. Can be done.
[0088]
According to the second aspect of the invention, the detected values of the magnetic sensor elements at the same longitudinal direction position of the magnetic line sensors arranged in parallel in the parallel part output processing part are averaged or added, and the parallel part is obtained in the angle calculating part. Since the rotation angle of the magnetism generating means is calculated from the average or added value by the output processing unit, it is possible to detect the rotation angle with higher accuracy.
[0089]
According to the third aspect of the invention, the fundamental wave phase calculation unit collects the outputs of the entire magnetic line sensor and performs Fourier transform to obtain the phase of the fundamental wave, and the angle calculation unit uses the fundamental wave phase calculation unit. Since the angle of the magnetism generating means is calculated from the obtained fundamental wave phase, the rotation angle can be calculated quickly and accurately, and even when the magnetic line sensors are discontinuously arranged. is there.
[0090]
According to the invention of claim 4, the weighting unit converts the detection value of the magnetic line sensor so that it becomes the maximum near zero of the magnetic field distribution and there is almost no detection value at a position away from zero. As a result, a data string having a weight near zero is created, and the angle calculation unit calculates the rotation angle of the magnetism generating means by calculating the moment around the center of gravity using two-dimensional coordinates based on the data string. As a result, the rotation angle can be calculated quickly and accurately.
[0091]
According to the fifth to seventh aspects of the present invention, the zero cross position is obtained by the least square approximation of the line to the data, the sum of the difference between the output and the reference waveform, or the correlation value between the output and the reference waveform. The accuracy of the angular position can be further improved.
[0092]
According to the eighth aspect of the invention, the angle calculation means performs pulse conversion on the calculation result of the rotation angle and outputs the pulse signal, so that an incremental signal can be output as the rotation angle output.
[0093]
According to the ninth aspect of the present invention, since the transmission unit wirelessly transmits information based on the calculation result of the angle calculation unit, a signal can be taken out without an output cable, and the installation work of the output cable is not required. be able to.
[0094]
According to the tenth aspect of the present invention, it is possible to arrange the rotation detecting device in the bearing and integrally form them, and it is possible to reduce the number of parts, the number of assembling steps, and the size of the bearing.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a rotation detection device according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing a magnetic line sensor and angle calculation means in the rotation detection device.
FIG. 3 is a block diagram showing a magnetic line sensor and angle calculation means in the rotation detection device.
FIG. 4 is a graph showing an output from a magnetic line sensor in the rotation detection device.
FIG. 5 is a block diagram showing a magnetic line sensor and angle calculation means in a rotation detection device according to a second embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a processing procedure in an angle calculation means in the rotation detection device, (a) a diagram showing an output waveform Si from a magnetic line sensor, and (b) an output waveform after performing a predetermined calculation. FIG. 5C shows the output waveform εi after further processing.
FIG. 7 is a diagram showing a screen of an output example in which image processing is performed by an angle calculation unit in the rotation detection device.
FIG. 8 is an explanatory diagram of a linear arrangement obtained by information based on the output screen of FIG.
FIG. 9 is an explanatory diagram showing a plurality of parallel magnetic line sensors in a rotation detection device according to a third embodiment of the present invention.
FIG. 10 is an explanatory diagram of output processing of a magnetic line sensor in the rotation detection device
FIG. 11 is a schematic diagram showing an output waveform from a magnetic line sensor and a hypothetical straight line in a rotation detection device according to a fourth embodiment of the present invention.
FIG. 12 is a schematic diagram showing a zero cross position of a magnetic line sensor in the rotation detection device.
FIG. 13 is a diagram showing a reference waveform (sign function) used in the process of the rotation detecting apparatus according to the fifth embodiment of the present invention (the same is applied to those used in the sixth embodiment).
FIG. 14 is a diagram showing a reference waveform (straight line) used in the process of the rotation detection device (the same applies to the waveform used in the sixth embodiment);
FIG. 15 is a graph showing an output waveform from a magnetic line sensor and a processed waveform D (i) in the rotation detection device;
FIG. 16 is a graph showing an output waveform from a magnetic line sensor and a processed waveform C (i) in a rotation detection device according to a sixth embodiment of the present invention;
FIG. 17 is a graph showing an output waveform (state before processing) from a magnetic line sensor according to another embodiment of the present invention;
[Explanation of symbols]
1 ... Rotation side member
2. Non-rotating side member
3. Magnetic generation means
4 ... Semiconductor chip
5 ... Magnetic line sensor
5A-5D ... Magnetic line sensor array
5a ... element
6 ... Angle calculation means
7 ... Fundamental wave phase calculator
8 ... Angle calculation unit
9 ... Weighting unit
10: Angle calculation unit

Claims (10)

A magnetism generating means disposed on the rotation side member and generating anisotropic magnetism with respect to a circumferential direction around the rotation center;
A magnetic line sensor disposed on a non-rotating side member facing the magnetism generating means and detecting magnetism of the magnetism generating means;
Angle calculating means for calculating the rotation angle of the magnetism generating means from the output detected by the magnetic line sensor;
A rotation detection device comprising:
The magnetic line sensor is arranged side by side around the center of rotation of the magnetism generating means, and the angle calculating means is configured such that each element characteristic accompanying the output detected by the magnetic line sensor or an accompanying circuit variation, Alternatively, the rotation detection device can calculate the rotation angle of the magnetism generating means while reducing the influence of noise. A plurality of the magnetic line sensors arranged in parallel, and the angle calculation means outputs a parallel part output that averages or adds the detection values of the magnetic sensor elements at the same longitudinal direction position of the magnetic line sensors arranged in parallel. The rotation detection device according to claim 1, further comprising: a processing unit; and an angle calculation unit that calculates a rotation angle of the magnetism generating unit from a value averaged or added by the parallel unit output processing unit. The angle calculation means includes a fundamental phase calculation unit that obtains a phase of a fundamental wave by performing a Fourier transform operation by collecting the outputs of the entire magnetic line sensor, and a fundamental wave obtained by the fundamental wave phase calculation unit. The rotation detection device according to claim 1, further comprising an angle calculation unit that calculates an angle of the magnetism generation unit from a phase. The angle calculation means weights the vicinity of the zero by converting the detection value of the magnetic line sensor so that the detection value becomes the maximum near zero of the magnetic field distribution and there is almost no detection value at a position away from zero. An angle for calculating the rotation angle of the magnetism generating means by calculating a moment around the center of gravity using a two-dimensional coordinate based on the data sequence generated by the weight applying unit The rotation detection device according to claim 1, further comprising a calculation unit. The angle calculation means detects a zero cross of a magnetic field distribution and calculates a rotation angle of the magnetism generation means, and the zero cross corresponds to candidate data near the zero cross position in the output of the magnetic line sensor. The rotation detection device according to claim 1, wherein the rotation detection device is obtained using least square approximation of a straight line. The angle calculation means calculates a rotation angle of the magnetism generation means by detecting a zero cross of a magnetic field distribution, and the sum of the differences between the output of the magnetic line sensor and a reference waveform is based on a prescribed number of data The rotation detection device according to claim 1, wherein a phase having the minimum value is obtained and a zero cross is obtained from the phase. The angle calculating means detects a zero cross of a magnetic field distribution and calculates a rotation angle of the magnetism generating means, and calculates a correlation value between the output of the magnetic line sensor and a reference waveform based on a prescribed number of data. 2. The rotation detecting device according to claim 1, wherein the rotation detection device calculates and obtains a phase having the maximum and minimum values, and obtains a zero cross based on the phase. The rotation detection apparatus according to claim 1, wherein the angle calculation unit performs pulse conversion on a calculation result of the rotation angle and outputs a pulse signal thereof. The rotation detection device according to claim 1, further comprising: a transmission unit that can wirelessly transmit information based on a calculation result by the angle calculation unit. The bearing with a rotation detection apparatus which incorporated the rotation detection apparatus as described in any one of Claims 1-9.

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