JP4167031B2 - Driving mechanism control device and surface texture measuring device - Google Patents

Description

【００１４】
第１段目の積分＋比例過程および第２段目の積分＋比例過程についてそれぞれ、作用力検出手段および駆動機構の周波数特性を加味して、応答のゲインを最大にするようにこの時定数Ｔを定める。すると、この駆動機構の特性から要求される周波数領域においては、応答速度が速く、かつ、安定した駆動制御を行うことができる。
【００１５】
本発明の駆動機構の制御装置において、前記第１段目の積分＋比例過程および前記第２段目の積分＋比例過程のそれぞれの時定数は等しいことが好ましい。
【００１６】
このような構成によれば、第１段目の積分＋比例過程と第２段目の積分＋比例過程の回路を同一とできるので、回路構成を単純化することができる。
【００１７】
本発明の駆動機構の制御装置において、前記可動部材の変位量を検出する変位量検出手段を備え、前記駆動機構は前記可動部材を微小変位させる微動機構および前記微動機構とともに前記可動部材を大変位させる粗動機構を備え、前記変位情報算出手段は、予め設定された前記可動部材の所定作用力と前記作用力検出手段で検出された作用力の差に基づいて前記変位情報を算出し、前記微動機構は、前記作用力を帰還情報として駆動制御され、前記粗動機構は、前記微動機構の変位量を予め設定された定常変位とするバランス変位量に対して前記変位情報算出手段で算出された前記変位情報を帰還情報として駆動制御されることが好ましい。
【００１８】
このような構成において、可動部材は、微動機構によって微小範囲で変位され、さらに、可動部材は、微動機構とともに粗動機構によって大変位される。このとき、可動部材の変位量は、変位量検出手段によって検出される。
【００１９】
ここで、微動機構および粗動機構は、可動部材に対する作用力が予め設定された所定値になるようにそれぞれ駆動機構の制御装置によって駆動制御される。さらに、微動機構の可動部材が予め設定される定常変位（バランス変位量）となるように微動機構および粗動機構は駆動制御される。
つまり、制御対象は、微動機構および粗動機構であり、この制御の目標は、可動部材への作用力を一定にすることと、微動機構の可動部材の変位位置が常に定常位置（バランス変位量）になるようにすることである。
【００２０】
この目標を達成するため、まず、作用力検出手段で可動部材に作用する作用力を帰還情報として検出する。検出された作用力と予め設定された所定作用力との差を求める。これにより、可動部材に過剰に作用する作用力を算出できる。この過剰に作用する作用力から変位情報算出手段によって変位情報を得る。すなわち、作用力を所定値にするために必要な可動部材の変位量を算出することができる。変位情報算出手段で算出された変位情報に基づいて微動機構を駆動させる。すると、可動部材に作用する作用力を所定値とすることができる。
【００２１】
粗動機構は、変位情報算出手段で算出された変位情報と微動機構定常位置として設定されたバランス変位量との差を動作信号として駆動制御される。すると、微動機構の変位ではまかなえない変位量は粗動機構によって補われ、微動機構の変位量を所定量とすることができる。
【００２２】
本発明によれば、作用力検出手段で検出された作用力と所定作用力との差から変位情報算出手段で変位情報を算出し、この変位情報に基づいて可動部材に作用する作用力を一定とするように微動機構を駆動することができる。この際、変位情報算出手段は、二段の比例＋積分過程であるので、応答が速く、かつ、安定である。
変位情報算出手段で算出された変位情報を粗動機構にフィードバックするので、微動機構の変位量を所定量にするように粗動機構を駆動することができる。
本発明によれば、微動機構の高速応答性を損なうことなく駆動機構の可動範囲（測定範囲）を拡大することができる。
【００２３】
本発明の駆動機構の制御装置において、前記粗動機構は、前記変位量検出手段により検出された前記変位量と前記変位情報算出手段で算出された前記変位情報との差の微分情報を速度帰還情報として駆動制御されることが好ましい。
このような構成によれば、粗動機構は、変位量検出手段により検出された可動部材の変位量と変位情報算出手段で算出された微動機構の変位情報との差の微分情報を速度帰還情報として駆動制御されるので、粗動機構の速度帰還情報を得るためのセンサーをわざわざ設けなくとも制御特性を改善することが出来る。
【００２４】
本発明の表面性状測定装置は、上述したいずれかに記載の駆動機構の制御装置を用いて構成され、前記可動部材は、被測定物表面に接近または離隔されて被測定物表面を走査する測定子であり、前記作用力は、前記被測定物表面と前記測定子とが関与する際に変化する状態量であって、前記変位検出手段の検出値により前記被測定物の表面性状を検出することを特徴とする。
【００２５】
このような構成によれば、上述した駆動機構の制御装置の効果を奏する表面形状測定装置を構成することができる。すなわち、被測定物表面に沿って測定子を走査させる際に、測定子に作用する作用力を一定にしつつ、速やかにかつ安定に測定子を走査することができる。
駆動機構が微動機構と粗動機構で構成されていれば、測定子に作用する作用力を一定とするように微動機構を駆動することができる。このとき、応答が速く、かつ、安定に微動機構を駆動制御することができる。変位情報算出手段で算出された変位情報とバランス変位量との差を粗動機構にフィードバックするので、微動機構の変位量を所定量にするように粗動機構を駆動することができる。よって、微小凹凸と大凹凸を有する被測定物表面に沿って測定子を走査させる場合でも、測定子を速やかにかつ安定に走査させることができる。その結果、測定データのばらつき幅が小さくかつ測定速度を向上させることができる。
【００２６】
【発明の実施の形態】
以下、本発明の駆動機構の制御装置および表面性状測定装置の実施形態を図面に基づいて説明する。
図１に、本発明の表面性状測定装置の一実施形態を示す。
この表面性状測定装置１は、被測定物Ｗに接触される可動部材としての測定子２と、測定子２を変位させる駆動機構３と、測定子２の変位を検出する変位量検出センサ４と、測定子２が被測定物Ｗに接触した際に被測定物表面から測定子２に作用する作用力を検出する作用力検出手段としての作用力センサ５と、駆動機構３の駆動を制御する駆動機構の制御装置としての駆動機構制御回路６とを備えて構成されている。
【００２７】
駆動機構３は、測定子２を微小範囲で変位させる微動機構３２と、この微動機構３２とともに測定子２を大変位させる粗動機構３３とを備えて構成されている。
微動機構３２は、粗動機構３３の可動部３３３に固定される微動固定部３２１と、この微動固定部３２１に設けられた圧電素子３２２とを備えて構成されている。圧電素子３２２の下端側に測定子２が設けられている。
粗動機構３３は、駆動機構３の筐体であるハウジング３１に固定された永久磁石３３１と、この永久磁石３３１による磁界中を上下方向に移動する可動コイル３３２とを備えた電磁アクチュエータで構成されている。可動コイル３３２の下端には可動コイル３３２と一体的に移動する可動部３３３が設けられている。可動部３３３は、ハウジング３１と一体化された粗動固定部３３４をガイドするエアーベアリング３３５によって滑動可能に保持されている。
さらに、駆動機構３のハウジング３１は、三次元座標測定機（不図示）などに取り付けられＸ、Ｙ、Ｚ駆動軸によって移動される。
【００２８】
変位量検出センサ４は、微動機構３２の下端と測定子２の上端との間に設けられた可動要素４１に保持され微動機構３２および粗動機構３３の変位方向と平行方向に移動するスケール４２と、粗動固定部３３４に設けられスケール４２の変位量を検出する検出器４３とを備えたリニアエンコーダで構成されている。変位量検出センサ４は、測定子２のハウジング３１に対する変位量を検出する。すなわち、変位量検出センサ４は、粗動機構３３および微動機構３２の合成変位量を検出することになる。変位量検出センサ４による検出結果は変位量信号として出力される。
【００２９】
作用力センサ５は、測定子２の上端に設けられ、測定子２の歪み量を検出する歪みゲージなどで構成されている。作用力センサ５は、測定子２に作用する作用力を検出し、検出結果を作用力信号として出力する。
【００３０】
駆動機構制御回路６は、微動機構３２を駆動制御する微動機構制御回路６１と、粗動機構３３を駆動制御する粗動機構制御回路７１とを備えて構成されている。
微動機構制御回路６１は、作用力センサ５から出力される作用力信号を換算して作用力情報を出力する作用力検出回路６２と、予め設定された指定作用力と作用力検出回路６２からの作用力情報とを比較して作用力の差を出力する作用力比較器６３と、作用力比較器６３から出力される作用力の差から微動機構３２についての微動変位情報を算出する変位情報算出手段としての微動変位情報算出回路６４と、微動変位情報算出回路６４からの微動変位情報に基づいて微動機構３２の圧電素子３２２を駆動する微動機構駆動回路６８とを備えて構成されている。
【００３１】
作用力検出回路６２は、作用力センサ５より出力された作用力信号から測定子２に作用する力を算出する。例えば、作用力センサ５が歪みゲージであった場合、歪みゲージによって検出された測定子２の歪み量を測定子２に作用している力に換算して、換算結果を作用力情報として出力する。ここに、作用力検出回路６２と作用力センサ５とから作用力検出手段が構成されている。
【００３２】
作用力比較器６３は、予め設定された指定作用力と作用力検出回路６２からの作用力情報とを比較して、測定子２に実際に作用している作用力と指定された作用力との差を算出して出力する。
指定作用力は、予め設定された一定の作用力で測定子２と被測定物表面とが接触を保つように設定されるものである。測定子２と被測定物表面とが一定の作用力で接触するように測定子２を被測定物表面の形状（粗さ、うねり）に沿って変位させることにより、測定子２の変位は被測定物の表面性状を反映したものとなる。
【００３３】
微動変位情報算出回路６４は、作用力比較器６３から出力された指定作用力と作用力情報との差より、作用力を指定作用力に保つために必要な微動機構３２の変位量を算出して微動変位情報として出力する。
微動変位情報算出回路６４は、図２に示されるように、２段の比例＋積分過程（ＰＩ過程）を行う２段ＰＩ回路６５と、ノイズフィルタとしてのローパスフィルタ（ＬＰＦ）６４１およびバンドエリミネートフィルタ（ＢＥＦ）６４２とを備える。
【００３４】
２段ＰＩ回路６５は、直列に連結された二つの比例＋積分回路で構成され、第１段目の比例＋積分過程を行う第１ＰＩ回路６６と、第２段目の比例＋積分過程を行う第２ＰＩ回路６７とを備える。
第１ＰＩ回路６６および第２ＰＩ回路６７は、図３に示されるように、互いに並列された積分回路６６１および増幅回路６６２と、積分回路６６１からの出力と増幅回路６６２からの出力とを加算する加算回路６６３とを備える。
第１ＰＩ回路６６および第２ＰＩ回路６７は同一の回路構成であり、すなわち時定数およびゲイン定数も同一である。このとき、時定数は、作用力検出回路６２と作用力センサ５とから構成される作用力検出手段および、微動機構駆動回路６８と圧電素子３２２とから構成される駆動手段の周波数特性を加味して、応答が最大となるように定める。つまり、制御系の遮断周波数が出来るだけ高くなるように時定数を定める。例えば、安定性を損なわない範囲内で増幅回路６６２の比例ゲインを可能な限り高く設定し、さらに積分回路６６１の積分ゲインを応答が最大になるように設定する。このようにして、安定かつ速応性も向上した応答特性を得る。
微動変位情報算出回路６４で算出された微動変位情報は、微動機構３２の圧電素子３２２を駆動させる微動機構駆動回路６８へ出力される。
【００３５】
微動機構駆動回路６８は、圧電素子３２２を駆動させるための駆動アンプで構成され、微動変位情報により指令される変位量から圧電素子３２２に印加する電圧を算出し、この電圧を圧電素子３２２に印加する。
微動変位情報算出回路６４で算出された微動変位情報は、指定作用力（目標値）と測定子２に実際に作用している作用力（制御量）との偏差を解消するために必要な測定子２の変位量を表している。よって、この微動変位情報分の測定子２の変位によって、測定子２に作用する作用力が指定作用力で一定となるように制御される。
【００３６】
粗動機構制御回路７１は、粗動機構３３の変位量を制御する粗動変位制御部７２と、粗動機構３３の駆動速度を制御する粗動速度制御部７５と、粗動機構３３へ与えられる電流値を制御する粗動電流制御部８１と、粗動機構３３を駆動する粗動機構駆動回路８４とを備えて構成されている。
【００３７】
粗動変位制御部７２は、微動機構３２について予め設定されたバランス変位量と微動変位情報算出回路６４で算出された微動変位情報とを比較してこの差（変位偏差）を出力する位置比較器７３と、位置比較器７３から出力される信号値（変位偏差）に基づいて速度指令値を生成する位置補償器７４とを備えている。
微動機構３２について予め設定されるバランス変位量とは、微動機構３２の可能変位幅において微動機構３２の可動部である測定子２の定常状態における変位量のことである。微動変位情報算出回路６４で算出される微動変位情報がこのバランス変位量から外れた場合には、微動機構３２の変位量をバランス変位量に戻すように、バランス変位量と微動変位情報との差（変位偏差）の分を粗動機構３３で補うことになる。
位置比較器７３は、バランス変位量と微動変位情報算出回路６４からの微動変位情報とを比較してこの差を算出する。すなわち、微動機構３２の変位量をバランス変位量に戻すために必要な粗動機構３３の変位量を算出する。
位置補償器７４は、位置比較器７３からの信号に基づいて粗動機構３３の速度指令値を生成する。位置補償器７４は、例えば、位相補償器や、ＰＩ補償器や、フィルタ等を備えて構成される。位置補償器７４からの出力は、粗動機構３３の速度指令値として次の粗動速度制御部７５に送られる。
【００３８】
粗動速度制御部７５は、変位検出センサ４からの変位量信号を換算して測定子２の実変位量情報を出力する変位量検出回路７６と、変位量検出回路７６による実変位情報と微動変位情報算出回路６４による微動変位情報とを比較してこの差を出力する変位比較器７７と、変位比較器７７により算出された結果を微分して速度情報を得る微分回路７８と、微分回路７８からの速度情報と粗動変位制御部７２からの粗動速度指令値とを比較してこの差（速度偏差）を算出する速度比較器７９と、速度比較器７９からの信号値より電流指令値を生成する速度補償器８０とを備えて構成されている。
【００３９】
変位量検出回路７６は、変位量検出センサ４から出力された変位量信号から測定子２の変位量を算出する。例えば、変位量検出センサ４が光電式リニアエンコーダであれば、検出器４３から出力されるパルスをカウントすることにより測定子２の実変位量を算出する。ここに、変位量検出回路７６と変位量検出センサ４とから変位量検出手段が構成されている。
【００４０】
変位比較器７７は、微動変位情報算出回路６４で算出される微動変位情報と変位量検出回路７６で算出される測定子２の実変位量とを比較してこの差を算出する。
微分回路７８は、変位比較器７７からの出力値の微分値を算出する。ここで、微動変位情報の微分値は微動機構３２の駆動速度を意味し、測定子２の実変位量の微分値は微動機構３２および粗動機構３３の合成駆動速度を意味することになる。よって、微分回路７８からの出力値は、粗動機構３３の速度を意味することになる。
【００４１】
速度比較器７９は、粗動変位制御部７２からの粗動速度指令値と微分回路７８からの速度情報とを比較してこの差を算出する。ここで、粗動変位制御部７２からの粗動速度指令値は、微動機構３２の変位量をバランス変位量に戻すために必要な粗動機構３３の駆動速度を意味し、微分回路７８からの速度情報は、現在の粗動機構３３の駆動速度を意味している。従って、速度比較器７９からの出力は、粗動機構３３にさらに加えるべき駆動速度を意味することになる。
【００４２】
速度補償器８０は、速度比較器７９からの信号を特性補償するとともに、速度比較器７９からの信号（速度情報）に基づいて、速度比較器７９で得られた速度を達成するために粗動機構３３に印加すべき電流値を求める。速度補償器８０は、例えば、位相補償器や、ＰＩ補償器や、フィルタ等を備えて構成され、周波数特性を改善するためのものである。
速度補償器８０で得られた電流指令値は、粗動電流制御部８１に送られる。
【００４３】
粗動電流制御部８１は、速度補償器８０からの電流指令値と粗動機構３３の図示しない電流センサから帰還される帰還電流値とを比較してこの差を算出する電流比較器８２と、電流比較器８２からの出力値を特性補償する電流補償器８３とを備えて構成されている。
電流比較器８２は、速度補償器８０からの電流値と粗動機構３３から帰還される帰還電流値との差を算出する。速度補償器８０からの電流指令値は、粗動機構３３にさらに加えるべき速度に見合う電流値であり、帰還電流値は現在粗動機構３３に印加されている電流値である。よって、電流比較器８２から出力される電流値は、粗動機構３３にさらに加えるべき電流値を意味することになる。
電流補償器８３からの出力電流は、粗動機構駆動回路８４に送られる。
【００４４】
粗動機構駆動回路８４は、粗動機構３３である電磁アクチュエータを駆動するコイルアンプで構成されている。粗動機構駆動回路８４からの電流が粗動機構３３の可動コイル３３２に印加されて、可動コイル３３２が変位される。
【００４５】
このような構成からなる表面性状測定装置１の動作について説明する。
まず、目標値を設定する。つまり、作用力比較器６３に入力する指定作用力と、位置比較器７３に入力する微動機構３２のバランス変位量を設定する。この目標値をとるように駆動機構３（微動機構３２、粗動機構３３）が駆動機構制御回路６によって制御されることになる。
【００４６】
測定子２を被測定物表面に接触させ、駆動機構３が取り付けられた三次元座標測定機のＸ軸もしくはＹ軸、つまり被測定物表面に沿って測定子２を走査させる駆動軸によって駆動機構３を移動させる。この三次元座標測定機の駆動量と、変位量検出回路７６による駆動機構３の駆動量（実変位情報）とから測定子２の変位量を取得して、被測定物表面性状の測定データを得ることができる。
【００４７】
測定子２が被測定物表面に接触すると、このとき被測定物表面から測定子２に作用する作用力は、作用力センサ５で検出され、作用力信号として作用力検出回路６２に出力される。作用力検出回路６２は、作用力信号を換算して測定子２に作用している作用力を算出し、作用力情報として作用力比較器６３に出力する。作用力比較器６３は、指定作用力と作用力情報とを比較してこの差（作用力偏差）を算出し、微動変位情報算出回路６４に出力する。
【００４８】
微動変位情報算出回路６４では、２段ＰＩ回路６５によって比例＋積分過程を二回行うことにより、作用力偏差を解消するために必要な測定子２の移動量を算出する。２段ＰＩ回路６５からの出力は、２次ＬＰＦ６４１およびＢＥＦ６４２に通されてノイズが除去され、微動変位情報として出力される。
【００４９】
微動変位情報算出回路６４から出力される微動変位情報は、分岐され、一方は微動機構駆動回路６８に送られ微動機構３２を駆動させ、他方は粗動機構制御回路７１に送られて粗動機構３３の駆動制御にまわされる。
微動機構駆動回路６８は、微動変位情報により指令された変位量分だけ微動機構３２を駆動させるために必要な電圧値を微動機構３２の圧電素子３２２に印加する。これにより、測定子２の作用力を指定作用力で一定となるように測定子２が変位される。
【００５０】
微動変位情報算出回路６４で算出された微動変位情報は、粗動機構制御回路７１の内部でさらに分岐され、一方は位置比較器７３に送られて粗動機構３３の変位量の制御を行うループをなし、他方は変位比較器７７に送られ粗動機構３３の速度制御のループをなす。
【００５１】
微動変位情報とバランス変位量とが位置比較器７３で比較されこの差（位置偏差）が算出される。位置比較器７３からの出力は、位置補償器７４に送られ、微動機構３２の変位量をバランス変位量に戻すために必要な速度指令として速度比較器７９に出力される。
【００５２】
測定子２の変位量は、変位量検出センサ４で検出され、変位量信号として変位量検出回路７６に送られる。変位量検出回路７６により変位量信号は測定子２の実変位量に換算されて変位比較器７７に送られる。一方、変位量検出回路７６からの測定子２の実変位量は、外部に出力されて、測定データとなる。
【００５３】
微動変位情報と変位量検出回路７６から出力された実変位情報とは変位比較器７７で比較されこの差が算出される。変位比較器７７からの出力は微分回路７８に送られて微分され速度情報として速度比較器７９に出力される。
【００５４】
速度比較器７９では、位置補償器７４からの出力値と微分回路７８からの速度情報とが比較されてこの差が算出される。算出結果は、粗動機構３３にさらに加えるべき速度を意味し、速度補償器８０によって、粗動機構３３にさらに加えるべき電流値に変換される。速度補償器８０からの出力は、電流比較器８２に出力される。
【００５５】
電流比較器８２において、速度補償器８０から出力される電流指令値と粗動機構３３からの帰還電流値とが比較され、この差が電流補償器８３に出力される。電流補償器８３からの出力は、粗動機構３３にさらに加えるべき電流値を意味し、粗動機構駆動回路８４に出力される。粗動機構駆動回路８４は、電流補償器８３から入力される電流値に基づいて粗動機構３３の可動コイル３３２に電流を印加する。すると、可動コイル３３２が永久磁石の磁界中で変位され、粗動機構３３が駆動される。
可動コイル３３２が変位されると、可動部３３３が変位されて、このとき微動機構３２と測定子２が変位される。
【００５６】
このように微動機構３２および粗動機構３３によって測定子２が変位される。測定子２の変位量は、変位量検出回路７６から外部に出力される。変位量検出回路７６による測定子２の実変位量は三次元座標測定機の駆動量とともに処理され、被測定物表面の測定データとされる。
【００５７】
このような構成からなる表面性状測定装置１によれば、次の効果を奏することができる。
（１）駆動機構３は、測定子２を微小範囲で変位させる微動機構３２と、測定子２を微動機構３２とともに大変位させる粗動機構３３とを備えている。よって、測定子２を被測定物表面の粗さ等の微小凹凸とうねり等の大凹凸に追従させることができる。その結果、粗さおよびうねりを有する被測定物表面を測定することができる。
（２）作用力センサ５で検出された作用力信号から作用力検出回路６２で測定子２に作用する作用力を算出し、この作用力を微動変位情報算出回路６４で二回積分することにより、測定子２の変位に関する情報を得ることができる。
【００５８】
（３）微動変位情報算出回路６４は、積分過程にさらに比例過程を加えた比例＋積分過程を二段行う二段ＰＩ回路６５を備えている。さらに、この二段ＰＩ回路６５の時定数は作用力から変位情報までの応答周波数の範囲で最大のゲインが得られるように設定されている。よって、この微動変位情報算出回路６４によって算出された変位情報によって微動機構３２を微動機構駆動回路６８で駆動させると、測定子２を被測定物表面に沿って速やかにかつ安定に走査させることができる。
ここで、図４に微動機構制御回路６１の閉ループの周波数特性を示す。図４（Ａ）にゲイン線図を示し、図４（Ｂ）に位相線図を示す。図４（Ａ）のゲイン線図により、約１０００Ｈｚまでは、減衰のないフラットなゲインが得られることが分かる。図４（Ｂ）の位相線図により、５０Ｈｚまでは−０．７ｄｅｇの遅れにとどまることが分かる。
すなわち、本実施形態の表面性状測定装置１によれば、測定データのばらつき幅を小さくしかつ測定速度を向上させることができる。
【００５９】
（４）２段ＰＩ回路６５の第１ＰＩ回路６６と第２ＰＩ回路６７は同一の回路を用いるので、回路構成を簡便なものにできる。
（５）バランス変位量と微動変位情報算出回路６４で算出された微動変位情報との差を位置比較器７３で算出して粗動機構３３の動作信号とするので、微動機構３２の変位量をバランス変位量に戻すように粗動機構３３を駆動することができる。
【００６０】
（６）微動変位情報と変位量検出回路７６からの実変位情報との差を変位比較器７７で算出し、この算出結果の微分値を微分回路７８で算出する。この算出結果である速度情報と位置補償器７４からの変位偏差との差を速度比較器７９で算出して粗動機構３３への動作信号とするので、微動機構３２の変位を微小範囲にするために粗動機構３３に対してさらに加えるべき速度を求めることができる。これは、制御対象の目標値を設定して、出力値を決める一般的な制御（定位制御）とは異なり、バランス変位量が与えられても、駆動機構３の実変位情報は一定値とはならない無定位制御系を用いている。すなわち、作用力一定制御系と無定位大変位制御系を結合させることにより、駆動機構３の周波数特性を改善している。
【００６１】
（７）駆動機構３の応答特性が改善されることにより、被測定物表面の形状に対する測定子２の追従性が良くなるので、測定子２で被測定物表面を走査する走査速度を向上させることができる。従来の測定子２の走査速度は、１〜５μｍ／ｓであるとされているが（計測と制御、４１（２００２）２８１−２８６、保坂他）、本実施形態によれば、従来の１０倍以上の走査速度を実現することができる。
【００６２】
尚、本発明の駆動機構の制御装置および表面性状測定装置は、上記実施形態にのみ限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
微動変位情報算出回路６４は、２段のＰＩ回路であるとしたが、比例回路を含まない２段の積分回路であって、作用力から二回の積分過程で変位情報を算出するものであってもよい。
【００６３】
駆動機構３が微動機構３２と粗動機構３３とから構成されるものについて説明したが、例えば、粗動機構３３と粗動機構制御回路７１とを含まないで、微動機構３２と微動機構制御回路６１とからなる表面性状測定装置１であってもよい。すなわち、微動機構３２のみからなる駆動機構３を微動機構制御回路６１からなる駆動機構制御回路６で駆動制御してもよい。
【００６４】
粗動機構３３および微動機構３２の構成は上記実施形態にのみ限られるものではなく、可動部材を変位させることができるものであればよい。例えば、微動機構３２は圧電素子３２２ではなく電磁アクチュエータで構成されていてもよい。また、粗動機構３３の電磁アクチュエータはハウジング３１に固定コイルを固定し、この固定コイルの磁界中を可動部３３３に設けた永久磁石が移動する構成としても良い。この場合、駆動電流を供給する配線が固定部側に設けられるので、構造が簡素になる他、可動コイル３３２への電気配線が不要となり、断線などの故障を避けることができ、信頼性が向上する。
【００６５】
さらに、可動部３３３は、エアーベアリング３３５によって保持される構成を示したが、平行板ばねやリニヤガイドによって保持される構成としても良い。このようにすれば、空圧源が不要となり、駆動機構が簡素になる。
また、粗動機構３３は、微動変位情報を帰還する位置ループと、速度情報を帰還する速度ループと、電流値を帰還する電流ループを備えた例を示したが、必要に応じて電流ループや速度ループを省略した簡素な構成としても良い。
【００６６】
さらに、変位量検出センサ４としてエンコーダを用いる例を示したが、その他の変位を検出できるセンサを用いても良い。例えば、電気マイクロや光を用いた非接触センサでも良い。要は、必要な測定可能幅と分解能、精度を備えたセンサであれば良い。特に光センサを用いれば、微動機構３２における微動可動部である測定子２の重量を軽減できるので、高速応答が得られる。
また、本実施形態においては、微動変位情報算出回路６４において、ノイズフィルタとしてローパスフィルタ（ＬＰＦ）６４１およびバンドエリミネートフィルタ（ＢＥＦ）６４２とを用いたが、これに限らず、他のノイズフィルタでも良く、さらに特に必要がなければ、これらのフィルタを設けない構成としても良い。
【００６７】
本実施形態において用いた補償器７４、８０、８３などは動作信号を操作量に変換することが主な機能であるが、これにフィードバック制御系の特性を改善するための、各種の制御要素を備えても良い。
また、作用力センサ５として歪みゲージを用いる例を示したが、その他の力センサを用いても良い。例えば、圧電素子を用いても良い。しかし、一般的には、歪みゲージの方が、直線性が良く、精度の高い測定が行える。
【００６８】
さらに、測定子２は圧電素子３２２の下端側に設ける構成を示したが、微動固定部３２１に対して測定子２が移動可能にガイドされるガイド機構を設けても良い。このようにすれば、粗動機構３３の可動部３３３の移動方向と微動機構３２の微動可動部の測定子２の移動方向を同一方向とすることが容易になる。この場合のガイド機構としては、エアーベアリング、平行板ばね、リニヤガイドなどを用いることができる。特に、粗動機構３３のガイド面と微動機構３２のガイド面を同一にすれば、移動方向を同一にすることが、より容易になるので、精度の高い駆動機構を構成することが出来る。
【００６９】
また、圧電素子３２２への給電は電気配線による他、粗動固定部３２１に設けた給電コイルと可動部３３３に設けた受電コイルを電磁結合させて行っても良い。このようにすれば、可動部への電気配線が不要となり、断線などの故障を避けることができ、信頼性が向上する他、配線のたわみや配線重量による駆動機構３への加圧などの外乱要因を減らすことができるので、微動機構３２や粗動機構３３の制御性能が向上する。
【００７０】
さらに、本実施形態では、微動変位情報によって微動機構３２と粗動機構３３の両方が常時制御される構成を示したが、この微動変位情報が所定幅以下の場合は、粗動機構制御回路７１の制御量を変化させない構成としても良い。つまり、微動変位情報が所定幅以下の場合は、粗動機構駆動回路の出力が変化しない構成とし、変位が微小幅に留まる場合は、粗動機構３３の可動部３３３を、その位置に停止させたままとすることによって、駆動機構３全体の制御性能（周波数応答）をさらに改善できる構成としても良い。
【００７１】
この実施形態においては、測定子２が被測定物Ｗに接触した際に被測定物表面から測定子２に作用する作用力を検出する作用力センサ５を用いる表面性状測定装置を示したが、これに限らず、非接触測定を行う表面性状測定装置であっても良い。例えば、測定子２と被測定物Ｗとの間の原子間力が一定となるように測定子２を制御して被測定物Ｗの表面性状を測定する原子間力顕微鏡であっても良く、この場合、力センサの検出結果に対して本発明を実施できる。また、圧電素子などを用いて測定子２を軸方向に超音波振動させる加振手段をさらに備え、測定子２が被測定物Ｗに近接した際に、測定子２と被測定物Ｗとの間に生じる音圧を音圧センサによって測定し、この音圧が一定となるように測定子２を制御して被測定物Ｗの表面性状を測定する表面性状測定装置であっても良く、この場合、音圧センサの検出結果に対して本発明を実施できる。このような非接触表面性状測定機によれば、被測定物へ傷をつけることなく、高速に信頼度の高い測定を行うことができる。
【００７２】
また、測定子２として例えば、特開2001−91206号公報に記載されたタッチセンサあるいは加振型プローブを用いることも出来る。この構成においては、加振手段によって測定子を軸方向に振動させ、測定子が被測定物に接触したことによって変化した軸方向振動を検出手段によって検出する。この際に、測定子と被測定物の接触の度合い（作用力）によって振動振幅が変化するので、この変化を検知して作用力を算出することができる。この場合は接触式の測定となるが、高精度、高感度、低測定圧で測定が行えるという利点を備える。
【００７３】
本発明の駆動機構の制御装置は、表面性状測定装置１の駆動機構３を駆動制御するものに限定されず、可動部材に作用する作用力を一定にしながら可動部材を変位させる駆動機構３を駆動制御するものであればよい。
【００７４】
【発明の効果】
以上、説明したように本発明の駆動機構の制御装置によれば、応答速度が速くかつ安定した応答を示すことができ、本発明の表面性状測定装置によれば、測定データのばらつき幅を小さくしかつ測定速度を向上させ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】本発明の表面性状測定装置の一実施形態を示す図である。
【図２】前記実施形態において、微動変位情報算出回路の構成を示す図である。
【図３】前記実施形態において、ＰＩ回路の構成を示す図である。
【図４】前記実施形態において、微動機構制御回路の閉ループの周波数特性を示す図である。（Ａ）はゲイン線図であり、（Ｂ）は位相線図である。
【図５】従来の表面性状測定装置を示す図である。
【符号の説明】
１ 表面性状測定装置
２ 測定子（可動部材）
３ 駆動機構
４ 変位量検出センサ
５ 作用力センサ
６ 駆動機構制御回路
３２ 微動機構
３３ 粗動機構
４２ スケール
４３ 検出器
６１ 微動機構制御回路
６２ 作用力検出回路
６４ 微動変位情報算出回路
６５ 二段ＰＩ回路
６６ 第１ＰＩ回路
６７ 第２ＰＩ回路
７１ 粗動機構制御回路
７２ 粗動変位制御部
７５ 粗動速度制御部
７６ 変位量検出回路
７８ 微分回路
８１ 粗動電流制御部
６６１ 積分回路
６６２ 増幅回路
６６３ 加算回路
Ｗ 被測定物[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive mechanism control device and a surface texture measuring device. For example, a movable member that is movable with respect to the main body, and a surface roughness of the object to be measured by scanning the surface of the object to be measured by the control device of the drive mechanism that controls the drive mechanism that drives the movable member and the movable member. The present invention relates to a surface texture measuring apparatus that measures surface texture such as swell, contour, contour shape, and roundness.
[0002]
[Background]
A control device for a drive mechanism that has a movable member that can move with respect to the main body and that drives and controls the drive mechanism that drives the movable member is known. 2. Description of the Related Art A surface property measuring apparatus that moves along a surface of a measurement object and measures the roughness or undulation of the surface of the measurement object is known.
As shown in FIG. 5, the surface texture measuring apparatus 1 includes a probe 10 having a measuring element 2 as a movable member that contacts the workpiece W and a driving mechanism 3 that drives the measuring element 2 in the vertical direction. Displacement amount detecting means 9 for detecting the displacement amount of the probe 2 is provided.
The drive mechanism 3 includes a fine movement mechanism 32 that moves the probe 2 in a minute range, and a coarse movement mechanism 33 that moves the probe 2 together with the fine movement mechanism 32. The fine movement mechanism 32 and the coarse movement mechanism 33 are driven and controlled by the drive mechanism control circuit 6. The fine movement mechanism 32 is constituted by, for example, a solid element such as a piezoelectric element. The coarse movement mechanism 33 is configured by, for example, an electromagnetic actuator.
Further, the probe 10 is attached to a three-dimensional coordinate measuring machine, a roundness measuring machine, a contour shape measuring machine (not shown), and the like, and is driven by X, Y, and Z driving shafts.
[0003]
In such a configuration, the probe 2 is scanned and moved along the surface of the object to be measured by driving the fine movement mechanism 32 and the coarse movement mechanism 33, respectively. At this time, the measuring element 2 is moved by the displacement of the fine movement mechanism 32 with respect to the fine roughness of the surface of the object to be measured, and the displacement amount of the fine movement mechanism 32 with respect to a large displacement such as a wave of the surface of the object to be measured. Is moved by the displacement of the coarse movement mechanism 33 so as to be within a small displacement. By detecting the displacement amount of the measuring element 2 when the measuring element 2 is moved along the surface of the object to be measured by the displacement amount detecting means 9, the surface property of the object to be measured can be measured. In this way, by driving the fine movement mechanism 32 and the coarse movement mechanism 33 respectively, it is possible to efficiently perform the measurement object W having a fine unevenness of nanometer order and a large unevenness of micrometer order like a semiconductor wafer. Can be measured.
[0004]
When the fine movement mechanism 32 and the coarse movement mechanism 33 are driven and controlled, the respective drive mechanisms 3 are feedback-controlled by the drive mechanism control circuit 6.
In general, in the control of the drive mechanism 3 as described above for controlling the movement amount of the probe 2 that is a movable member, the displacement amount of the movable member 2 is calculated from the acceleration generated in the movable member 2, and the displacement amount and the control target are calculated. The feedback information was obtained from the difference. For example, the displacement amount of the movable member 2 is obtained by integrating acceleration twice, and the difference between the displacement amount and the control target is fed back as feedback information.
[0005]
[Problems to be solved by the invention]
However, when the measuring element 2 is displaced following the roughness and undulation of the surface of the object to be measured that changes from time to time, if the integration process is simply performed twice as in the prior art, the phase of the response to the input is changed. It tends to be greatly delayed. As a result, according to the control system including the double integration process as described above, the phase lag is increased, and the phase margin of the control system is reduced. Therefore, the operation is likely to be unstable, and the control system is extremely slow. Problem arises. That is, there is a problem that the measurement data greatly fluctuates and the measurement accuracy is deteriorated, or the scanning movement speed must be extremely low.
[0006]
Such a problem is common to not only the control device of the drive mechanism 3 used in the surface texture measuring device 1 but also the feedback control performed by the control device of the drive mechanism 3 that drives the movable member 2.
[0007]
The first object of the present invention is to provide a control device for a drive mechanism that solves the conventional problems and exhibits a fast response speed and a stable response. The second object of the present invention is to provide measurement data An object of the present invention is to provide a surface texture measuring device that reduces the variation width and improves the measurement speed.
[0008]
[Means for Solving the Problems]
  The present inventionThe drive mechanism control device is a drive mechanism control device that drives and controls a drive mechanism that displaces the movable member, and includes an acting force detection means that detects an acting force acting on the movable member, and the acting force detection means. Displacement information calculation means for calculating displacement information of the movable member by integrating the acting force detected by step 2 in a two-stage integration process,The displacement information calculating means is a two-stage integral + proportional process further comprising a proportional process for the acting force,The drive mechanism is driven and controlled so that the acting force is constant based on the displacement information of the movable member obtained by the displacement information calculation means.
[0009]
In such a configuration, the movable member is displaced by the drive mechanism so that the acting force on the movable member becomes constant at a predetermined value set in advance. Here, the acting force on the movable member is, for example, a pressing force applied from the measurement target to the movable member when the movable member is pressed against the measurement target, for example, between the movable member and the measurement target. In the case where an attractive force between atoms is generated, it means an acting force acting on the movable member from an object in which the movable member is involved, such as an atomic force.
The acting force detecting means detects the acting force acting on the movable member and outputs the detection result to the displacement information calculating means.
The displacement information calculation means calculates the displacement information of the movable member by integrating this acting force in a two-stage integration process.
If the force is integrated twice, it becomes the same dimension as the displacement, so that the displacement information calculating means can obtain the displacement information of the movable member.
For example, if a predetermined value set in advance is subtracted from the action force detected by the action force detection means and this is double-integrated, the displacement of the movable member necessary to make the action force acting on the movable member a predetermined value The amount can be calculated.
Thus, the displacement information calculated by the displacement information calculation means is fed back, and the movable member is displaced by the drive mechanism. Then, the drive mechanism can be controlled so that the acting force acting on the movable member becomes constant.
[0011]
  AlsoThe control of the drive mechanism can be stabilized by adjusting the proportional gain and the integral gain for each integral + proportional process (PI control). In the case of a two-stage integration process alone, the phase delay due to integration is doubled, and the phase margin in feedback control is extremely reduced. As a result, the closed-loop frequency response is degraded, so only low-speed control is possible. . On the other hand, if PI control is added with a proportional process, the phase characteristics are improved and the response of the drive mechanism can be speeded up.
[0012]
  The present inventionIn the drive mechanism control apparatus, the time constants of the first stage integral + proportional process and the second stage integral + proportional process of the displacement information calculation means maximize the response of the drive control. To be stipulatedIs preferred.
[0013]
In the integral + proportional process, if the parameter of the Laplace transform (Laplace operator) is s, the transfer function G (s) of the integral + proportional process is expressed by the following equation, where k and j are coefficients of the integral process and the proportional process, respectively. It is represented by

[0014]
The time constant T is set so as to maximize the response gain in consideration of the frequency characteristics of the acting force detecting means and the drive mechanism for the first stage integral + proportional process and the second stage integral + proportional process, respectively. Determine. Then, in the frequency region required from the characteristics of the drive mechanism, the response speed is high and stable drive control can be performed.
[0015]
  The present inventionIn the drive mechanism control apparatus, the time constants of the first stage integral + proportional process and the second stage integral + proportional process are equal.Is preferred.
[0016]
According to such a configuration, the circuit of the first stage integration + proportional process and the second stage integration + proportional process can be made the same, and therefore the circuit configuration can be simplified.
[0017]
  The present inventionThe drive mechanism control apparatus further comprises a displacement amount detecting means for detecting a displacement amount of the movable member, and the drive mechanism includes a fine movement mechanism for finely displacing the movable member, and a coarse movement for large displacement of the movable member together with the fine movement mechanism. A displacement mechanism, wherein the displacement information calculation means calculates the displacement information based on a difference between a predetermined action force of the movable member set in advance and an action force detected by the action force detection means, and the fine movement mechanism Is driven and controlled by using the acting force as feedback information, and the coarse movement mechanism is calculated by the displacement information calculation means with respect to a balance displacement amount in which a displacement amount of the fine movement mechanism is set to a preset steady displacement. Drive control using displacement information as feedback informationIs preferred.
[0018]
In such a configuration, the movable member is displaced in a minute range by the fine movement mechanism, and further, the movable member is largely displaced by the coarse movement mechanism together with the fine movement mechanism. At this time, the displacement amount of the movable member is detected by the displacement amount detection means.
[0019]
Here, the fine movement mechanism and the coarse movement mechanism are driven and controlled by the control device of the drive mechanism so that the acting force on the movable member becomes a predetermined value set in advance. Further, the fine movement mechanism and the coarse movement mechanism are driven and controlled so that the movable member of the fine movement mechanism has a steady displacement (balance displacement amount) set in advance.
That is, the objects to be controlled are the fine movement mechanism and the coarse movement mechanism, and the goal of this control is to make the acting force on the movable member constant and the displacement position of the movable member of the fine movement mechanism is always the steady position (balance displacement amount). ).
[0020]
In order to achieve this goal, first, the acting force acting on the movable member is detected as feedback information by the acting force detection means. The difference between the detected acting force and a predetermined acting force set in advance is obtained. Thereby, the acting force which acts excessively on the movable member can be calculated. Displacement information is obtained by the displacement information calculation means from the acting force acting excessively. That is, it is possible to calculate the amount of displacement of the movable member necessary for setting the acting force to a predetermined value. The fine movement mechanism is driven based on the displacement information calculated by the displacement information calculating means. Then, the acting force acting on the movable member can be set to a predetermined value.
[0021]
The coarse movement mechanism is driven and controlled by using the difference between the displacement information calculated by the displacement information calculation means and the balance displacement amount set as the fine movement mechanism steady position as an operation signal. Then, the displacement amount that cannot be covered by the displacement of the fine movement mechanism is compensated by the coarse movement mechanism, and the displacement amount of the fine movement mechanism can be set to a predetermined amount.
[0022]
According to the present invention, the displacement information calculating means calculates the displacement information from the difference between the acting force detected by the acting force detecting means and the predetermined acting force, and the acting force acting on the movable member is fixed based on the displacement information. The fine movement mechanism can be driven as follows. At this time, since the displacement information calculation means is a two-stage proportional + integration process, the response is fast and stable.
Since the displacement information calculated by the displacement information calculating means is fed back to the coarse movement mechanism, the coarse movement mechanism can be driven so that the displacement amount of the fine movement mechanism is a predetermined amount.
According to the present invention, the movable range (measurement range) of the drive mechanism can be expanded without impairing the high-speed response of the fine movement mechanism.
[0023]
  The present inventionIn the drive mechanism control apparatus, the coarse movement mechanism uses differential information of a difference between the displacement amount detected by the displacement amount detection means and the displacement information calculated by the displacement information calculation means as speed feedback information. Drive controlledIs preferred.
  According to such a configuration, the coarse movement mechanism uses the differential feedback information of the difference between the displacement amount of the movable member detected by the displacement amount detection means and the displacement information of the fine movement mechanism calculated by the displacement information calculation means. Therefore, the control characteristics can be improved without having to provide a sensor for obtaining speed feedback information of the coarse motion mechanism.
[0024]
  The present inventionThe surface texture measuring device ofMentioned aboveThe movable member is a measuring element that scans the surface of the object to be measured while approaching or being separated from the surface of the object to be measured. It is a state quantity that changes when the surface of the object to be measured and the probe are involved, and the surface property of the object to be measured is detected by the detection value of the displacement detection means.
[0025]
  According to such a configuration,Mentioned aboveA surface shape measuring device that exhibits the effect of the control device of the drive mechanism can be configured. That is, when the measuring element is scanned along the surface of the object to be measured, the measuring element can be scanned quickly and stably while keeping the acting force acting on the measuring element constant.
  If the drive mechanism is composed of a fine movement mechanism and a coarse movement mechanism, the fine movement mechanism can be driven so that the acting force acting on the measuring element is constant. At this time, the fine movement mechanism can be driven and controlled stably with a quick response. Since the difference between the displacement information calculated by the displacement information calculation means and the balance displacement amount is fed back to the coarse movement mechanism, the coarse movement mechanism can be driven so that the displacement amount of the fine movement mechanism is a predetermined amount. Therefore, even when the measuring element is scanned along the surface of the object to be measured having minute irregularities and large irregularities, the measuring element can be scanned quickly and stably. As a result, the variation width of the measurement data is small and the measurement speed can be improved.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a drive mechanism control device and a surface texture measuring device according to the present invention will be described below with reference to the drawings.
FIG. 1 shows an embodiment of the surface texture measuring device of the present invention.
The surface texture measuring device 1 includes a measuring element 2 as a movable member that is in contact with the workpiece W, a drive mechanism 3 that displaces the measuring element 2, and a displacement detection sensor 4 that detects the displacement of the measuring element 2. The driving force sensor 5 as an acting force detecting means for detecting the acting force acting on the measuring element 2 from the surface of the object to be measured when the measuring element 2 comes into contact with the object W to be measured, and the drive of the driving mechanism 3 are controlled. A drive mechanism control circuit 6 serving as a drive mechanism control device is provided.
[0027]
The drive mechanism 3 includes a fine movement mechanism 32 that displaces the probe 2 in a very small range, and a coarse movement mechanism 33 that moves the probe 2 together with the fine movement mechanism 32.
The fine movement mechanism 32 includes a fine movement fixing section 321 fixed to the movable section 333 of the coarse movement mechanism 33 and a piezoelectric element 322 provided in the fine movement fixing section 321. A measuring element 2 is provided on the lower end side of the piezoelectric element 322.
The coarse movement mechanism 33 is configured by an electromagnetic actuator that includes a permanent magnet 331 fixed to a housing 31 that is a housing of the drive mechanism 3 and a movable coil 332 that moves in a vertical direction in a magnetic field generated by the permanent magnet 331. ing. A movable portion 333 that moves integrally with the movable coil 332 is provided at the lower end of the movable coil 332. The movable part 333 is slidably held by an air bearing 335 that guides a coarse movement fixing part 334 integrated with the housing 31.
Furthermore, the housing 31 of the drive mechanism 3 is attached to a three-dimensional coordinate measuring machine (not shown) or the like and is moved by X, Y, and Z drive shafts.
[0028]
The displacement detection sensor 4 is held by a movable element 41 provided between the lower end of the fine movement mechanism 32 and the upper end of the measuring element 2 and moves in a direction parallel to the displacement direction of the fine movement mechanism 32 and the coarse movement mechanism 33. And a linear encoder provided with a detector 43 that detects the amount of displacement of the scale 42 provided in the coarse motion fixing unit 334. The displacement amount detection sensor 4 detects the displacement amount of the probe 2 with respect to the housing 31. That is, the displacement amount detection sensor 4 detects the combined displacement amount of the coarse movement mechanism 33 and the fine movement mechanism 32. The detection result by the displacement detection sensor 4 is output as a displacement signal.
[0029]
The acting force sensor 5 is provided at the upper end of the measuring element 2 and is composed of a strain gauge or the like that detects the amount of distortion of the measuring element 2. The acting force sensor 5 detects the acting force acting on the measuring element 2 and outputs the detection result as an acting force signal.
[0030]
The drive mechanism control circuit 6 includes a fine movement mechanism control circuit 61 that drives and controls the fine movement mechanism 32 and a coarse movement mechanism control circuit 71 that drives and controls the coarse movement mechanism 33.
The fine movement mechanism control circuit 61 converts an action force signal output from the action force sensor 5 and outputs action force information, and a preset designated action force and action force detection circuit 62 outputs the action force information. An action force comparator 63 that compares the action force information and outputs a difference in action force, and displacement information calculation that calculates fine movement displacement information for the fine movement mechanism 32 from the difference in action force output from the action force comparator 63. A fine movement displacement information calculation circuit 64 as a means and a fine movement mechanism drive circuit 68 that drives the piezoelectric element 322 of the fine movement mechanism 32 based on the fine movement displacement information from the fine movement displacement information calculation circuit 64 are configured.
[0031]
The acting force detection circuit 62 calculates the force acting on the measuring element 2 from the acting force signal output from the acting force sensor 5. For example, when the acting force sensor 5 is a strain gauge, the strain amount of the measuring element 2 detected by the strain gauge is converted into a force acting on the measuring element 2, and the conversion result is output as acting force information. . Here, the acting force detection circuit 62 and the acting force sensor 5 constitute an acting force detection means.
[0032]
The action force comparator 63 compares the designated action force set in advance with the action force information from the action force detection circuit 62, and the action force actually acting on the measuring element 2 is compared with the designated action force. The difference is calculated and output.
The designated acting force is set such that the measuring element 2 and the surface of the object to be measured are kept in contact with each other with a predetermined constant acting force. By displacing the measuring element 2 along the shape (roughness, swell) of the surface of the object to be measured so that the measuring element 2 and the surface of the object to be measured are in contact with each other with a constant acting force, It reflects the surface properties of the measurement object.
[0033]
The fine movement displacement information calculation circuit 64 calculates the amount of displacement of the fine movement mechanism 32 required to keep the applied force at the specified applied force from the difference between the specified applied force output from the applied force comparator 63 and the applied force information. Output as fine movement displacement information.
As shown in FIG. 2, the fine displacement information calculation circuit 64 includes a two-stage PI circuit 65 that performs a two-stage proportional + integration process (PI process), a low-pass filter (LPF) 641 as a noise filter, and a band eliminate filter. (BEF) 642.
[0034]
The two-stage PI circuit 65 is composed of two proportional + integration circuits connected in series. The first PI circuit 66 performs the first-stage proportional + integration process, and the second-stage proportional + integration process. And a second PI circuit 67.
As shown in FIG. 3, the first PI circuit 66 and the second PI circuit 67 add the integration circuit 661 and the amplification circuit 662 that are parallel to each other, and the addition that adds the output from the integration circuit 661 and the output from the amplification circuit 662 A circuit 663.
The first PI circuit 66 and the second PI circuit 67 have the same circuit configuration, that is, the time constant and the gain constant are also the same. At this time, the time constant takes into account the frequency characteristics of the acting force detecting means constituted by the acting force detecting circuit 62 and the acting force sensor 5 and the driving means constituted by the fine movement mechanism driving circuit 68 and the piezoelectric element 322. And determine the maximum response. That is, the time constant is determined so that the cutoff frequency of the control system is as high as possible. For example, the proportional gain of the amplifier circuit 662 is set as high as possible within a range that does not impair the stability, and the integral gain of the integration circuit 661 is set so that the response is maximized. In this way, a response characteristic that is stable and improved in quick response is obtained.
The fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 is output to the fine movement mechanism drive circuit 68 that drives the piezoelectric element 322 of the fine movement mechanism 32.
[0035]
The fine movement mechanism drive circuit 68 is composed of a drive amplifier for driving the piezoelectric element 322, calculates a voltage to be applied to the piezoelectric element 322 from the amount of displacement commanded by the fine movement displacement information, and applies this voltage to the piezoelectric element 322. To do.
The fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 is a measurement necessary for eliminating the deviation between the designated acting force (target value) and the acting force (control amount) actually acting on the probe 2. The amount of displacement of the child 2 is represented. Therefore, the acting force acting on the measuring element 2 is controlled to be constant at the specified acting force by the displacement of the measuring element 2 corresponding to the fine movement displacement information.
[0036]
The coarse movement mechanism control circuit 71 gives the coarse movement displacement control section 72 that controls the displacement amount of the coarse movement mechanism 33, the coarse movement speed control section 75 that controls the driving speed of the coarse movement mechanism 33, and the coarse movement mechanism 33. A coarse movement current control unit 81 that controls a current value to be generated, and a coarse movement mechanism drive circuit 84 that drives the coarse movement mechanism 33.
[0037]
The coarse movement displacement control unit 72 compares the amount of balance displacement set in advance for the fine movement mechanism 32 with the fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 and outputs this difference (displacement deviation). 73 and a position compensator 74 that generates a speed command value based on a signal value (displacement deviation) output from the position comparator 73.
The balance displacement amount set in advance for the fine movement mechanism 32 is a displacement amount in a steady state of the measuring element 2 that is a movable portion of the fine movement mechanism 32 within a possible displacement width of the fine movement mechanism 32. When the fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 deviates from the balance displacement amount, the difference between the balance displacement amount and the fine movement displacement information is set so that the displacement amount of the fine movement mechanism 32 is returned to the balance displacement amount. The amount of (displacement deviation) is supplemented by the coarse movement mechanism 33.
The position comparator 73 compares the balance displacement amount with the fine movement displacement information from the fine movement displacement information calculation circuit 64 to calculate this difference. That is, the amount of displacement of the coarse movement mechanism 33 required to return the displacement amount of the fine movement mechanism 32 to the balance displacement amount is calculated.
The position compensator 74 generates a speed command value for the coarse movement mechanism 33 based on the signal from the position comparator 73. The position compensator 74 includes, for example, a phase compensator, a PI compensator, and a filter. The output from the position compensator 74 is sent to the next coarse movement speed control unit 75 as a speed command value of the coarse movement mechanism 33.
[0038]
The coarse motion speed control unit 75 converts the displacement signal from the displacement detection sensor 4 and outputs the actual displacement information of the measuring element 2, and the actual displacement information and the fine motion by the displacement detection circuit 76. A displacement comparator 77 that compares the fine movement displacement information by the displacement information calculation circuit 64 and outputs this difference, a differentiation circuit 78 that obtains speed information by differentiating the result calculated by the displacement comparator 77, and a differentiation circuit 78. A speed comparator 79 that compares the speed information from the coarse motion displacement control unit 72 with the coarse motion speed command value to calculate the difference (speed deviation), and a current command value from the signal value from the speed comparator 79 And a speed compensator 80 for generating
[0039]
The displacement amount detection circuit 76 calculates the displacement amount of the measuring element 2 from the displacement amount signal output from the displacement amount detection sensor 4. For example, if the displacement detection sensor 4 is a photoelectric linear encoder, the actual displacement of the probe 2 is calculated by counting pulses output from the detector 43. Here, the displacement amount detection circuit 76 and the displacement amount detection sensor 4 constitute displacement amount detection means.
[0040]
The displacement comparator 77 compares the fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 with the actual displacement amount of the probe 2 calculated by the displacement amount detection circuit 76 and calculates this difference.
The differentiation circuit 78 calculates the differential value of the output value from the displacement comparator 77. Here, the differential value of the fine movement displacement information means the driving speed of the fine movement mechanism 32, and the differential value of the actual displacement amount of the measuring element 2 means the combined driving speed of the fine movement mechanism 32 and the coarse movement mechanism 33. Therefore, the output value from the differentiation circuit 78 means the speed of the coarse movement mechanism 33.
[0041]
The speed comparator 79 compares the coarse movement speed command value from the coarse movement displacement control unit 72 with the speed information from the differentiation circuit 78 and calculates this difference. Here, the coarse movement speed command value from the coarse movement displacement control unit 72 means the drive speed of the coarse movement mechanism 33 required to return the displacement amount of the fine movement mechanism 32 to the balance displacement amount. The speed information means the current driving speed of the coarse movement mechanism 33. Therefore, the output from the speed comparator 79 means a driving speed to be further applied to the coarse movement mechanism 33.
[0042]
The speed compensator 80 performs characteristic compensation on the signal from the speed comparator 79, and based on the signal (speed information) from the speed comparator 79, coarse motion is performed to achieve the speed obtained by the speed comparator 79. A current value to be applied to the mechanism 33 is obtained. The speed compensator 80 includes, for example, a phase compensator, a PI compensator, a filter, and the like, and is for improving frequency characteristics.
The current command value obtained by the speed compensator 80 is sent to the coarse current controller 81.
[0043]
The coarse motion current control unit 81 compares a current command value from the speed compensator 80 with a feedback current value fed back from a current sensor (not shown) of the coarse motion mechanism 33 to calculate the difference, and And a current compensator 83 for compensating characteristics of the output value from the current comparator 82.
The current comparator 82 calculates the difference between the current value from the speed compensator 80 and the feedback current value fed back from the coarse motion mechanism 33. The current command value from the speed compensator 80 is a current value corresponding to the speed to be further applied to the coarse motion mechanism 33, and the feedback current value is a current value currently applied to the coarse motion mechanism 33. Therefore, the current value output from the current comparator 82 means a current value to be further added to the coarse movement mechanism 33.
The output current from the current compensator 83 is sent to the coarse movement mechanism drive circuit 84.
[0044]
The coarse movement mechanism drive circuit 84 includes a coil amplifier that drives an electromagnetic actuator that is the coarse movement mechanism 33. The current from the coarse movement mechanism drive circuit 84 is applied to the movable coil 332 of the coarse movement mechanism 33, and the movable coil 332 is displaced.
[0045]
The operation of the surface texture measuring apparatus 1 having such a configuration will be described.
First, a target value is set. That is, the specified acting force input to the acting force comparator 63 and the balance displacement amount of the fine movement mechanism 32 input to the position comparator 73 are set. The drive mechanism 3 (fine movement mechanism 32, coarse movement mechanism 33) is controlled by the drive mechanism control circuit 6 so as to take this target value.
[0046]
The driving mechanism is driven by a driving shaft that causes the measuring element 2 to contact the surface of the object to be measured and scans the measuring element 2 along the X or Y axis of the three-dimensional coordinate measuring machine to which the driving mechanism 3 is attached, that is, the surface of the measuring object. 3 is moved. The displacement amount of the probe 2 is obtained from the drive amount of the three-dimensional coordinate measuring machine and the drive amount (actual displacement information) of the drive mechanism 3 by the displacement amount detection circuit 76, and the measurement data of the surface property of the object to be measured is obtained. Obtainable.
[0047]
When the measuring element 2 comes into contact with the surface of the object to be measured, the acting force acting on the measuring element 2 from the surface of the object to be measured at this time is detected by the acting force sensor 5 and output to the acting force detection circuit 62 as an acting force signal. . The acting force detection circuit 62 calculates an acting force acting on the measuring element 2 by converting the acting force signal, and outputs it to the acting force comparator 63 as acting force information. The acting force comparator 63 compares the designated acting force with the acting force information, calculates this difference (acting force deviation), and outputs it to the fine movement displacement information calculating circuit 64.
[0048]
The fine movement displacement information calculation circuit 64 calculates the amount of movement of the probe 2 necessary to eliminate the acting force deviation by performing the proportional + integration process twice by the two-stage PI circuit 65. The output from the two-stage PI circuit 65 is passed through the secondary LPF 641 and the BEF 642 to remove noise, and is output as fine movement displacement information.
[0049]
The fine movement displacement information output from the fine movement displacement information calculation circuit 64 is branched, and one is sent to the fine movement mechanism drive circuit 68 to drive the fine movement mechanism 32, and the other is sent to the coarse movement mechanism control circuit 71 to send the coarse movement mechanism. 33 is used for drive control.
The fine movement mechanism drive circuit 68 applies a voltage value necessary to drive the fine movement mechanism 32 by the amount of displacement commanded by the fine movement displacement information to the piezoelectric element 322 of the fine movement mechanism 32. Thereby, the measuring element 2 is displaced so that the acting force of the measuring element 2 becomes constant at the designated acting force.
[0050]
The fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 is further branched inside the coarse movement mechanism control circuit 71, and one is sent to the position comparator 73 to control the displacement amount of the coarse movement mechanism 33. The other is sent to the displacement comparator 77 to form a loop for controlling the speed of the coarse movement mechanism 33.
[0051]
The fine movement displacement information and the balance displacement amount are compared by the position comparator 73, and the difference (position deviation) is calculated. The output from the position comparator 73 is sent to the position compensator 74 and is output to the speed comparator 79 as a speed command necessary for returning the displacement amount of the fine movement mechanism 32 to the balance displacement amount.
[0052]
The displacement amount of the probe 2 is detected by the displacement amount detection sensor 4 and sent to the displacement amount detection circuit 76 as a displacement amount signal. The displacement amount signal is converted into an actual displacement amount of the measuring element 2 by the displacement amount detection circuit 76 and sent to the displacement comparator 77. On the other hand, the actual displacement amount of the probe 2 from the displacement amount detection circuit 76 is output to the outside and becomes measurement data.
[0053]
The fine displacement information and the actual displacement information output from the displacement detection circuit 76 are compared by a displacement comparator 77 to calculate the difference. The output from the displacement comparator 77 is sent to the differentiation circuit 78 and differentiated and output to the speed comparator 79 as speed information.
[0054]
The speed comparator 79 compares the output value from the position compensator 74 with the speed information from the differentiating circuit 78 and calculates the difference. The calculation result means a speed to be further applied to the coarse movement mechanism 33, and is converted into a current value to be further applied to the coarse movement mechanism 33 by the speed compensator 80. The output from the speed compensator 80 is output to the current comparator 82.
[0055]
In the current comparator 82, the current command value output from the speed compensator 80 and the feedback current value from the coarse motion mechanism 33 are compared, and this difference is output to the current compensator 83. The output from the current compensator 83 means a current value to be further applied to the coarse movement mechanism 33 and is output to the coarse movement mechanism drive circuit 84. The coarse movement mechanism drive circuit 84 applies a current to the movable coil 332 of the coarse movement mechanism 33 based on the current value input from the current compensator 83. Then, the movable coil 332 is displaced in the magnetic field of the permanent magnet, and the coarse movement mechanism 33 is driven.
When the movable coil 332 is displaced, the movable portion 333 is displaced, and at this time, the fine movement mechanism 32 and the measuring element 2 are displaced.
[0056]
Thus, the measuring element 2 is displaced by the fine movement mechanism 32 and the coarse movement mechanism 33. The displacement amount of the probe 2 is output from the displacement amount detection circuit 76 to the outside. The actual displacement amount of the measuring element 2 by the displacement amount detection circuit 76 is processed together with the driving amount of the three-dimensional coordinate measuring machine to obtain measurement data on the surface of the object to be measured.
[0057]
According to the surface texture measuring apparatus 1 having such a configuration, the following effects can be obtained.
(1) The drive mechanism 3 includes a fine movement mechanism 32 that displaces the measuring element 2 in a minute range, and a coarse movement mechanism 33 that causes the measuring element 2 to be largely displaced together with the fine movement mechanism 32. Therefore, the measuring element 2 can be made to follow the micro unevenness such as the roughness of the surface of the object to be measured and the large unevenness such as the undulation. As a result, the surface of the object to be measured having roughness and undulation can be measured.
(2) By calculating the acting force acting on the measuring element 2 by the acting force detection circuit 62 from the acting force signal detected by the acting force sensor 5, this acting force is integrated twice by the fine movement displacement information calculating circuit 64. Information regarding the displacement of the probe 2 can be obtained.
[0058]
(3) The fine displacement information calculation circuit 64 includes a two-stage PI circuit 65 that performs a proportional + integration process in two stages by adding a proportional process to the integration process. Further, the time constant of the two-stage PI circuit 65 is set so that the maximum gain can be obtained in the range of the response frequency from the acting force to the displacement information. Therefore, when the fine movement mechanism 32 is driven by the fine movement mechanism drive circuit 68 based on the displacement information calculated by the fine movement displacement information calculation circuit 64, the probe 2 can be scanned quickly and stably along the surface of the object to be measured. it can.
Here, FIG. 4 shows the frequency characteristics of the closed loop of the fine movement mechanism control circuit 61. FIG. 4A shows a gain diagram, and FIG. 4B shows a phase diagram. It can be seen from the gain diagram in FIG. 4A that a flat gain without attenuation is obtained up to about 1000 Hz. It can be seen from the phase diagram of FIG. 4B that the delay is −0.7 deg until 50 Hz.
That is, according to the surface texture measuring device 1 of the present embodiment, it is possible to reduce the variation width of the measurement data and improve the measurement speed.
[0059]
(4) Since the first PI circuit 66 and the second PI circuit 67 of the two-stage PI circuit 65 use the same circuit, the circuit configuration can be simplified.
(5) Since the difference between the balance displacement amount and the fine movement displacement information calculated by the fine movement displacement information calculation circuit 64 is calculated by the position comparator 73 and used as the operation signal of the coarse movement mechanism 33, the displacement amount of the fine movement mechanism 32 is calculated. The coarse movement mechanism 33 can be driven to return to the balance displacement amount.
[0060]
(6) The difference between the fine movement displacement information and the actual displacement information from the displacement detection circuit 76 is calculated by the displacement comparator 77, and the differential value of this calculation result is calculated by the differentiation circuit 78. Since the difference between the speed information, which is the calculation result, and the displacement deviation from the position compensator 74 is calculated by the speed comparator 79 and used as an operation signal to the coarse movement mechanism 33, the displacement of the fine movement mechanism 32 is set to a minute range. Therefore, the speed to be further applied to the coarse movement mechanism 33 can be obtained. This is different from general control (localization control) in which a target value to be controlled is set and an output value is determined. Even if a balance displacement amount is given, the actual displacement information of the drive mechanism 3 is a constant value. A non-localized control system is used. That is, the frequency characteristic of the drive mechanism 3 is improved by combining the constant acting force control system and the non-localized large displacement control system.
[0061]
(7) Since the response characteristics of the drive mechanism 3 are improved, the followability of the measuring element 2 with respect to the shape of the surface of the object to be measured is improved. Therefore, the scanning speed for scanning the surface of the object to be measured with the measuring element 2 is improved. be able to. The scanning speed of the conventional probe 2 is 1 to 5 μm / s (measurement and control, 41 (2002) 281-286, Hosaka et al.). The above scanning speed can be realized.
[0062]
Note that the drive mechanism control device and the surface texture measuring device of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
Although the fine movement displacement information calculation circuit 64 is a two-stage PI circuit, it is a two-stage integration circuit that does not include a proportional circuit, and calculates displacement information in two integration processes from the applied force. May be.
[0063]
Although the drive mechanism 3 has been described with respect to the fine movement mechanism 32 and the coarse movement mechanism 33, for example, the fine movement mechanism 32 and the fine movement mechanism control circuit are not included without including the coarse movement mechanism 33 and the coarse movement mechanism control circuit 71. 61 may be used. That is, the drive mechanism 3 including only the fine movement mechanism 32 may be driven and controlled by the drive mechanism control circuit 6 including the fine movement mechanism control circuit 61.
[0064]
The configurations of the coarse movement mechanism 33 and the fine movement mechanism 32 are not limited to the above-described embodiment, and any structure that can displace the movable member may be used. For example, the fine movement mechanism 32 may be configured by an electromagnetic actuator instead of the piezoelectric element 322. The electromagnetic actuator of the coarse movement mechanism 33 may be configured such that a fixed coil is fixed to the housing 31 and a permanent magnet provided on the movable portion 333 moves in the magnetic field of the fixed coil. In this case, since the wiring for supplying the driving current is provided on the fixed portion side, the structure is simplified, and the electric wiring to the movable coil 332 is not required, and failure such as disconnection can be avoided and the reliability is improved. To do.
[0065]
Furthermore, although the movable part 333 showed the structure hold | maintained by the air bearing 335, it is good also as a structure hold | maintained by a parallel leaf | plate spring or a linear guide. In this way, an air pressure source becomes unnecessary and the driving mechanism is simplified.
Moreover, although the coarse motion mechanism 33 showed the example provided with the position loop which feeds back fine-movement displacement information, the speed loop which feeds back velocity information, and the current loop which feeds back current value, a current loop, A simple configuration in which the speed loop is omitted may be used.
[0066]
Furthermore, although the example which uses an encoder as the displacement amount detection sensor 4 was shown, you may use the sensor which can detect the other displacement. For example, a non-contact sensor using an electric micro or light may be used. In short, any sensor having the necessary measurable width, resolution, and accuracy may be used. In particular, when an optical sensor is used, the weight of the measuring element 2 which is a fine movement movable part in the fine movement mechanism 32 can be reduced, so that a high-speed response can be obtained.
In this embodiment, the fine displacement information calculation circuit 64 uses the low-pass filter (LPF) 641 and the band-eliminate filter (BEF) 642 as noise filters. However, the present invention is not limited to this, and other noise filters may be used. If there is no particular need, these filters may not be provided.
[0067]
The compensators 74, 80, 83, etc. used in this embodiment mainly function to convert operation signals into manipulated variables. However, various control elements for improving the characteristics of the feedback control system are added thereto. You may prepare.
Moreover, although the example which uses a strain gauge as the action force sensor 5 was shown, you may use another force sensor. For example, a piezoelectric element may be used. However, in general, a strain gauge has better linearity and can perform highly accurate measurement.
[0068]
Further, the configuration in which the measuring element 2 is provided on the lower end side of the piezoelectric element 322 is shown, but a guide mechanism for guiding the measuring element 2 to be movable with respect to the fine movement fixing portion 321 may be provided. In this way, it becomes easy to make the moving direction of the movable part 333 of the coarse movement mechanism 33 and the moving direction of the measuring element 2 of the fine movement movable part of the fine movement mechanism 32 the same direction. As a guide mechanism in this case, an air bearing, a parallel leaf spring, a linear guide, or the like can be used. In particular, if the guide surface of the coarse movement mechanism 33 and the guide surface of the fine movement mechanism 32 are made the same, it becomes easier to make the movement directions the same, so that a highly accurate drive mechanism can be configured.
[0069]
Further, power feeding to the piezoelectric element 322 may be performed by electromagnetically coupling a power feeding coil provided in the coarse motion fixing portion 321 and a power receiving coil provided in the movable portion 333 in addition to electrical wiring. This eliminates the need for electrical wiring to the movable part, avoids failures such as disconnection, improves reliability, and causes disturbances such as wiring deflection and pressure applied to the drive mechanism 3 due to the weight of the wiring. Since the factors can be reduced, the control performance of the fine movement mechanism 32 and the coarse movement mechanism 33 is improved.
[0070]
Furthermore, in the present embodiment, the configuration in which both the fine movement mechanism 32 and the coarse movement mechanism 33 are always controlled by the fine movement displacement information is shown. However, when the fine movement displacement information is equal to or less than a predetermined width, the coarse movement mechanism control circuit 71 is shown. The control amount may not be changed. That is, when the fine movement displacement information is equal to or smaller than the predetermined width, the output of the coarse movement mechanism driving circuit is not changed, and when the displacement remains within the small width, the movable portion 333 of the coarse movement mechanism 33 is stopped at that position. It is good also as a structure which can further improve the control performance (frequency response) of the whole drive mechanism 3 by leaving as it is.
[0071]
In this embodiment, although the surface property measuring apparatus using the acting force sensor 5 for detecting the acting force acting on the measuring element 2 from the surface of the object to be measured when the measuring element 2 contacts the object to be measured W is shown, However, the present invention is not limited to this, and a surface texture measuring device that performs non-contact measurement may be used. For example, an atomic force microscope that controls the measuring element 2 so that the atomic force between the measuring element 2 and the object W to be measured is constant and measures the surface property of the object W to be measured may be used. In this case, the present invention can be implemented on the detection result of the force sensor. Further, a vibration means for ultrasonically vibrating the measuring element 2 in the axial direction using a piezoelectric element or the like is further provided, and when the measuring element 2 approaches the object to be measured W, the measuring element 2 and the object W to be measured are provided. A surface texture measuring device that measures the surface texture of the workpiece W by measuring the sound pressure generated between them with a sound pressure sensor and controlling the probe 2 so that the sound pressure is constant may be used. In this case, the present invention can be implemented on the detection result of the sound pressure sensor. According to such a non-contact surface texture measuring instrument, it is possible to perform highly reliable measurement at high speed without damaging the object to be measured.
[0072]
Further, for example, a touch sensor or a vibration type probe described in Japanese Patent Application Laid-Open No. 2001-91206 can be used as the measuring element 2. In this configuration, the measuring element is vibrated in the axial direction by the vibrating means, and the axial vibration that is changed by the contacting of the measuring element with the object to be measured is detected by the detecting means. At this time, since the vibration amplitude changes depending on the degree of contact (acting force) between the probe and the object to be measured, the acting force can be calculated by detecting this change. In this case, contact-type measurement is performed, but there is an advantage that measurement can be performed with high accuracy, high sensitivity, and low measurement pressure.
[0073]
The control device for the drive mechanism of the present invention is not limited to the drive control of the drive mechanism 3 of the surface texture measuring device 1, but drives the drive mechanism 3 that displaces the movable member while keeping the acting force acting on the movable member constant. Anything can be used.
[0074]
【The invention's effect】
As described above, according to the control device of the drive mechanism of the present invention, the response speed is high and a stable response can be shown. According to the surface texture measuring device of the present invention, the variation width of the measurement data is reduced. In addition, there is an excellent effect that the measurement speed can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a surface texture measuring apparatus according to the present invention.
FIG. 2 is a diagram showing a configuration of a fine movement displacement information calculation circuit in the embodiment.
FIG. 3 is a diagram illustrating a configuration of a PI circuit in the embodiment.
FIG. 4 is a diagram illustrating a closed loop frequency characteristic of the fine movement mechanism control circuit in the embodiment. (A) is a gain diagram, and (B) is a phase diagram.
FIG. 5 is a view showing a conventional surface texture measuring device.
[Explanation of symbols]
1 Surface texture measuring device
2 Measuring element (movable member)
3 Drive mechanism
4 Displacement detection sensor
5 Action force sensor
6 Drive mechanism control circuit
32 Fine movement mechanism
33 Coarse motion mechanism
42 scale
43 Detector
61 Fine movement mechanism control circuit
62 Force detection circuit
64 Fine movement displacement information calculation circuit
65 Two-stage PI circuit
66 First PI circuit
67 Second PI circuit
71 Coarse motion control circuit
72 Coarse motion displacement controller
75 Coarse motion speed controller
76 Displacement detection circuit
78 Differentiation circuit
81 Coarse current controller
661 Integration circuit
662 Amplifier circuit
663 Adder circuit
W DUT

Claims (6)

A drive mechanism control device for driving and controlling a drive mechanism for displacing a movable member,
An acting force detecting means for detecting an acting force acting on the movable member;
Displacement information calculation means for calculating displacement information of the movable member by integrating the action force detected by the action force detection means in a two-stage integration process;
The displacement information calculating means is a two-stage integral + proportional process further comprising a proportional process for the acting force,
An apparatus for controlling a drive mechanism, wherein the drive mechanism is driven and controlled so that the acting force is constant based on the displacement information of the movable member obtained by the displacement information calculation means. The drive mechanism control device according to claim 1 ,
The time constants of the first stage integral + proportional process and the second stage integral + proportional process of the displacement information calculating means are determined so as to maximize the response of the drive control. Control device for driving mechanism. The control device for a drive mechanism according to claim 2 ,
The drive mechanism control device according to claim 1, wherein time constants of the first stage integral + proportional process and the second stage integral + proportional process are equal. In the control device of the drive mechanism according to any one of claims 1 to 3 ,
Displacement amount detection means for detecting the displacement amount of the movable member,
The drive mechanism includes a fine movement mechanism that finely displaces the movable member and a coarse movement mechanism that largely displaces the movable member together with the fine movement mechanism,
The displacement information calculating means calculates the displacement information based on a difference between a predetermined acting force of the movable member set in advance and the acting force detected by the acting force detecting means,
The fine movement mechanism is driven and controlled using the acting force as feedback information,
The coarse movement mechanism is driven and controlled by using the displacement information calculated by the displacement information calculation means as feedback information with respect to a balance displacement amount in which the displacement amount of the fine movement mechanism is a preset steady displacement. The drive mechanism control device. The control device for a drive mechanism according to claim 4 ,
The coarse movement mechanism is drive-controlled using differential information of a difference between the displacement amount detected by the displacement amount detection unit and the displacement information calculated by the displacement information calculation unit as velocity feedback information. Control device for driving mechanism. It is comprised using the control apparatus of the drive mechanism in any one of Claims 1-5 ,
The movable member is a measuring element that scans the surface of the object to be measured while approaching or separated from the surface of the object to be measured;
The acting force is a state quantity that changes when the surface of the object to be measured and the probe are involved,
A surface texture measuring device for measuring a surface texture of the object to be measured based on a detection value of the displacement amount detecting means.

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