JP5032235B2 - Method and apparatus for detecting measurement position of resonance sensor - Google Patents

Method and apparatus for detecting measurement position of resonance sensor Download PDF

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JP5032235B2
JP5032235B2 JP2007202180A JP2007202180A JP5032235B2 JP 5032235 B2 JP5032235 B2 JP 5032235B2 JP 2007202180 A JP2007202180 A JP 2007202180A JP 2007202180 A JP2007202180 A JP 2007202180A JP 5032235 B2 JP5032235 B2 JP 5032235B2
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智徳 後藤
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Description

本発明は、共振特性を利用した共振センサの測定位置検出方法及び装置に係り、特に、形状測定機、３次元測定機、画像測定機等の共振センサが装着可能な測定機器に用いるのに好適な、加振手段により測定子を長手方向に共振振動させ、検出手段により測定子の共振に応じた出力信号を得て、測定子先端と測定対象との接触を検知するようにした共振センサの測定位置検出方法及び装置に関する。   The present invention relates to a resonance sensor measurement position detection method and apparatus using resonance characteristics, and is particularly suitable for use in a measuring instrument to which a resonance sensor such as a shape measuring machine, a three-dimensional measuring machine, and an image measuring machine can be attached. The resonance sensor is configured to detect the contact between the tip of the probe and the object to be measured by causing the probe to resonate in the longitudinal direction by the vibration means and obtaining an output signal corresponding to the resonance of the probe by the detection means. The present invention relates to a measurement position detection method and apparatus.

触針によるナノレベルでの表面形状測定で従来から用いられている手法を図１に示す。   FIG. 1 shows a conventionally used technique for measuring the surface shape at the nano level with a stylus.

図１（Ａ）は、測定対象１０の上でプローブ１２を移動させ、測定対象１０の凹凸によりプローブ１２にかかる原子間力が微妙に変化することを読取って、測定対象１０の凹凸を可視化する原子間力顕微鏡（ＡＦＭ）である。このＡＦＭによれば、原子レベルの凹凸を観測することが可能であるが、計測しているのは、原子間力が一定の面である。   FIG. 1A visualizes the unevenness of the measurement object 10 by moving the probe 12 over the measurement object 10 and reading that the atomic force applied to the probe 12 slightly changes due to the unevenness of the measurement object 10. It is an atomic force microscope (AFM). According to this AFM, it is possible to observe unevenness at the atomic level, but what is measured is a surface with a constant atomic force.

一方、図１（Ｂ）に示す粗さ計のような古典的な表面形状計測手法では、測定力がｍＮ程度あるため、測定対象１０の表面に引掻き傷が残り、硬さ一定の面を計測していることに相当する。   On the other hand, in the classic surface shape measurement method such as the roughness meter shown in FIG. 1 (B), since the measuring force is about mN, scratches remain on the surface of the measuring object 10, and a surface with a constant hardness is measured. It is equivalent to doing.

このように、センシング技術により、測定している物理量が異なる。   Thus, the physical quantity being measured differs depending on the sensing technology.

現在開発されている共振特性を利用した共振センサ（特許文献１参照）は、図１（Ｃ）に示す如く、測定対象１０とプローブ１２の相互作用を共振特性の変化として捉えようとするものである。この共振センサは、プローブ１２の先端径がμｍオーダーであり、測定対象１０の表面を傷付けない測定が可能であることから、局所的な弾性力一定の面を測定していると考えられる。   A resonance sensor (see Patent Document 1) that uses a resonance characteristic that is currently being developed attempts to capture the interaction between the measurement target 10 and the probe 12 as a change in the resonance characteristic, as shown in FIG. is there. In this resonance sensor, the tip diameter of the probe 12 is on the order of μm, and measurement is possible without damaging the surface of the measurement object 10, so it is considered that a surface having a constant elastic force is measured.

出願人が特許文献１で提案した共振センサは、図２に示す如く、μｍオーダーの径を持つダイヤモンドチップやルビー球等を先端２２Ａに付けた測定子（スタイラスと称する）２２に、加振用と検出用の２枚の圧電素子２４、２６を貼り付けた構造をしている。加振回路２８により共振センサ２０の加振用圧電素子２４を駆動して、スタイラス２２を長手方向（図の上下方向）に共振振動させると、検出用圧電素子２６からは、スタイラス２２の共振に応じた出力信号が得られる。この共振状態にあるスタイラス２２の先端２２Ａが測定対象と接触すると、その押込み量に応じて共振特性（周波数、位相、振幅）が変化し、検出用圧電素子２６の出力信号（検出信号とも称する）の振幅、周波数、位相が変化するので、検出回路３０で、この出力信号の変化を捉えることで、スタイラス先端２２Ａと測定対象との接触を検知することができる。接触を検知した時点での座標位置を読取るためのスケールとセンサ、あるいは測定対象の走査機構を備えることで、表面形状測定が可能になる。   As shown in FIG. 2, the resonance sensor proposed by the applicant in Patent Document 1 is applied to a probe (referred to as a stylus) 22 having a tip 22A with a diamond tip or ruby ball having a diameter of μm order. And two piezoelectric elements 24 and 26 for detection are attached. When the excitation piezoelectric element 24 of the resonance sensor 20 is driven by the excitation circuit 28 to cause the stylus 22 to resonate in the longitudinal direction (vertical direction in the figure), the detection piezoelectric element 26 causes the stylus 22 to resonate. A corresponding output signal is obtained. When the tip 22A of the stylus 22 in the resonance state comes into contact with the measurement object, the resonance characteristics (frequency, phase, amplitude) change according to the amount of pressing, and an output signal (also referred to as a detection signal) of the detection piezoelectric element 26. Therefore, the detection circuit 30 can detect the contact between the stylus tip 22A and the measurement object by detecting the change in the output signal. By providing a scale and a sensor for reading a coordinate position at the time when contact is detected, or a scanning mechanism to be measured, surface shape measurement can be performed.

このように、スタイラス２２の先端が測定対象と接触すると、検出用圧電素子２６の出力信号の振幅、周波数、位相が変化するが、ここでは、簡単のため、検出信号の振幅の変化を使って説明する。スタイラス２２が測定対象と接触した瞬間に、相互作用によりエネルギーの散逸が起こり、共振信号の振幅が減少する。ここで、更にスタイラスを押込んでいくと、検出信号の振幅は、スタイラス−測定対象間の距離に対して、図３に例示するように、スタイラス２２が測定対象１０の表面に接触を開始する位置（接触点）を境に、押込み量に比例して信号振幅が徐々に減少していく特性曲線となる。従って、信号振幅に閾値（図の例では９０％）を設定しておき、信号振幅が閾値を横切った時点でトリガー信号を発生させ、その時点での座標位置を測定点として読み取れば、タッチトリガー方式のセンサとして利用して座標計測が可能になる。   As described above, when the tip of the stylus 22 comes into contact with the measurement target, the amplitude, frequency, and phase of the output signal of the detection piezoelectric element 26 change. Here, for the sake of simplicity, the change in the amplitude of the detection signal is used. explain. At the moment when the stylus 22 comes into contact with the object to be measured, energy dissipation occurs due to the interaction, and the amplitude of the resonance signal decreases. Here, when the stylus is further pushed in, the amplitude of the detection signal is a position at which the stylus 22 starts to contact the surface of the measurement target 10 as illustrated in FIG. 3 with respect to the distance between the stylus and the measurement target. From the point of contact (contact point), it becomes a characteristic curve in which the signal amplitude gradually decreases in proportion to the pushing amount. Therefore, if a threshold value (90% in the example in the figure) is set for the signal amplitude, a trigger signal is generated when the signal amplitude crosses the threshold value, and the coordinate position at that point is read as a measurement point, the touch trigger Coordinate measurement is possible by using the sensor as a method.

特開２００２−３９３７３７号公報JP 2002-393737 A 特開平１０−１１１１４３号公報Japanese Patent Laid-Open No. 10-111143 特開平６−３１４０号公報JP-A-6-3140

ここで、スタイラス２２−測定対象１０間の相互作用が瞬間的に大きく変化する、スタイラス２２が測定対象１０と接触した瞬間を考えてみる。このとき、スタイラス２２のＱ値や共振周波数の変化量にも依存するが、検出信号は、図４に例示するように、過渡状態を経て定常状態へと変化する。   Here, consider the moment when the stylus 22 contacts the measuring object 10 where the interaction between the stylus 22 and the measuring object 10 changes greatly instantaneously. At this time, although depending on the Q value of the stylus 22 and the amount of change in the resonance frequency, the detection signal changes to a steady state through a transient state as illustrated in FIG.

一般には、検出信号が過渡状態にある間は計測を行なわず、定常状態になって検出信号が安定してから計測を行なう。因みに、強制振動調和振動子を考えれば分かるように、共振周波数をω0とすると、時定数τは、次式で表わされる。 In general, measurement is not performed while the detection signal is in a transient state, and measurement is performed after the detection signal is stabilized in a steady state. Incidentally, as can be seen by considering the forced vibration harmonic oscillator, when the resonance frequency is ω 0 , the time constant τ is expressed by the following equation.

τ＝２Ｑ／ω0 …（１） τ = 2Q / ω 0 (1)

しかしながら、従来の測定方法であると、スタイラス２２−測定対象１０間の相互作用が変化した直後から整定時間を経過するまでの過渡状態の間は計測できないので、例えポイント測定であっても、長い測定時間を必要とするという問題点を有していた。   However, the conventional measurement method cannot measure during a transient state from when the interaction between the stylus 22 and the measurement object 10 changes until the settling time elapses. It had the problem of requiring measurement time.

即ち、共振センサ２０では、図３に示したように、スタイラス２２−測定対象１０間の相互作用により検出信号の振幅が変化することを利用して、検出信号振幅が閾値を超えた時点でトリガーサンプリングを行なっている。このときの検出信号振幅は、定常状態での信号振幅である。   That is, the resonance sensor 20 is triggered when the detection signal amplitude exceeds the threshold value by using the change in the amplitude of the detection signal due to the interaction between the stylus 22 and the measurement target 10, as shown in FIG. Sampling is in progress. The detection signal amplitude at this time is a signal amplitude in a steady state.

従って、スタイラス２２が測定対象１０に接触直後から押し込んでいく過程において、常に定常状態の検出信号を観測するように、スタイラス２２の押し込み速度と時定数を考慮したサンプリングが必要である。例えば共振周波数３００ＫＨｚ、Ｑ値３００程度である場合、時定数τは約３００μ秒となり、ｎｍオーダーでの表面形状測定を行なう場合、押し込み速度をかなり低速にする必要がある。このように、定常状態における検出信号振幅の現象を利用したトリガーサンプリングでは、図５に例示するように、座標計測に長い時間を必要とする。   Therefore, in the process in which the stylus 22 is pushed into the measuring object 10 immediately after contact, sampling in consideration of the pushing speed and time constant of the stylus 22 is necessary so that a steady state detection signal is always observed. For example, when the resonance frequency is 300 KHz and the Q value is about 300, the time constant τ is about 300 μsec. When measuring the surface shape in the nm order, the indentation speed needs to be considerably low. As described above, in the trigger sampling using the phenomenon of the detection signal amplitude in the steady state, as shown in FIG. 5, a long time is required for coordinate measurement.

又、共振センサ２０においては、スタイラス２２の形状が薄い板状で、測定対象１０からの弾性力に対して等方的なセンサではないため、方向依存性によって特性曲線が変化する。又、測定対象表面に傷を付けない範囲では、スタイラスと測定対象表面との弾性的な相互作用によるものと考えられることから、スタイラス先端２２Ａ、測定対象１０の材質や、共振センサ２０に使っている圧電素子２４、２６の製造ロットによっても特性曲線が変化する。更には、共振センサ２０が置かれている温度や湿度といった環境によっても特性曲線は影響を受ける。これらの影響は、図６に例示するように、特性曲線の傾きの違いとなって現われる。そのため、閾値（図の例では８０％）によるトリガーサンプリングを行なうと、サンプリング時の特性曲線の傾きの違いにより大きな測定誤差を生じるという問題点を有していた。   Further, in the resonance sensor 20, since the stylus 22 has a thin plate shape and is not an isotropic sensor with respect to the elastic force from the measurement object 10, the characteristic curve changes depending on the direction dependency. Further, in a range where the surface of the measurement target is not damaged, it is considered that the stylus is caused by an elastic interaction between the surface of the measurement target, and therefore the stylus tip 22A, the material of the measurement target 10 and the resonance sensor 20 are used. The characteristic curve also changes depending on the production lot of the piezoelectric elements 24 and 26 that are present. Furthermore, the characteristic curve is also affected by the environment such as temperature and humidity where the resonance sensor 20 is placed. These effects appear as differences in the slope of the characteristic curve, as illustrated in FIG. Therefore, when trigger sampling is performed with a threshold value (80% in the example in the figure), there is a problem that a large measurement error occurs due to a difference in the slope of the characteristic curve at the time of sampling.

一方、特許文献２には、タッチ信号プローブの正弦波状の検出出力信号から振幅情報を検波抽出することにより得られた、低周波の状態変動成分と高周波のノイズ成分が重量された直流センサ信号から急激な振幅変化点でトリガー信号を生成する際に、低周波の状態変動成分のみの信号から基準信号を生成し、これと直流センサ信号を比較して、直流センサ信号の急激な直流レベル変動成分を高精度に検知することが記載され、特許文献３には、予め登録されたパターンとの相関により測定位置を推定することが記載されている。しかしながら、共振センサにそのまま用いても、十分な効果を上げることはできなかった。   On the other hand, Patent Document 2 discloses a DC sensor signal weighted with a low-frequency state fluctuation component and a high-frequency noise component obtained by detecting and extracting amplitude information from a sinusoidal detection output signal of a touch signal probe. When generating a trigger signal at an abrupt amplitude change point, a reference signal is generated from a signal with only a low-frequency state fluctuation component, and this is compared with the DC sensor signal to produce a sudden DC level fluctuation component of the DC sensor signal. Is detected with high accuracy, and Patent Document 3 describes that a measurement position is estimated based on a correlation with a previously registered pattern. However, even if it is used as it is for the resonance sensor, a sufficient effect cannot be obtained.

本発明は、前記従来の問題点を解決するべくなされたもので、測定時間を短縮して高速測定を可能にすると共に、共振センサの誤差要因の影響を減少させ、より高精度な測定を可能にして、使い勝手及び信頼性を向上し、更に、低価格化することを課題とする。   The present invention has been made to solve the above-mentioned conventional problems, shortens the measurement time and enables high-speed measurement, and reduces the influence of error factors of the resonance sensor, thereby enabling more accurate measurement. Thus, it is an object to improve usability and reliability and to further reduce the price.

本発明は、加振手段により測定子を長手方向に共振振動させ、検出手段により測定子の共振に応じた出力信号を得て、測定子先端と測定対象との接触を検知するようにした共振センサの測定位置検出方法において、共振状態の変化に追従させて安定な振動を持続するためのフィードバックによる発振制御を行なうと共に、該発振制御のためのフィードバック制御量の過渡的な変化から、測定子先端と測定対象との接触を検知して測定位置とする際に、前記接触を検知した後、測定子が測定対象に押し込まれて確認信号が得られた時に、正しい接触検知と判定することにより、前記課題を解決したものである。 According to the present invention, the resonance of the measuring element is caused to resonate in the longitudinal direction by the vibration means, the output signal corresponding to the resonance of the measuring element is obtained by the detecting means, and the contact between the tip of the measuring element and the measuring object is detected. In the measurement position detection method of the sensor, the oscillation control is performed by feedback to keep the stable vibration by following the change of the resonance state, and the measuring element is detected from the transient change of the feedback control amount for the oscillation control. By detecting the contact between the tip and the measurement object and setting it as the measurement position, after detecting the contact, when a check signal is obtained by pushing the probe into the measurement object, The above-mentioned problem is solved.

本発明は、又、加振手段により測定子を長手方向に共振振動させ、検出手段により測定子の共振に応じた出力信号を得て、測定子先端と測定対象との接触を検知するようにした共振センサの測定位置検出装置において、共振状態の変化に追従させて安定な振動を持続するためのフィードバックによる発振制御を行なう発振制御手段と、該発振制御のためのフィードバック制御量の過渡的な変化から、測定子先端と測定対象との接触を検知して測定位置とする手段と、前記接触を検知した後、測定子が測定対象に押し込まれた時に確認信号を出力する手段と、該確認信号が得られた時に、正しい接触検知と判定する手段と、を備えたことを特徴とする共振センサの測定位置検出装置を提供するものである。 In the present invention, the probe is resonantly vibrated in the longitudinal direction by the vibration means, and an output signal corresponding to the resonance of the probe is obtained by the detection means, so that contact between the probe tip and the measurement object is detected. In the resonance sensor measurement position detection apparatus, oscillation control means for performing oscillation control by feedback for keeping a stable vibration following the change of the resonance state, and a transient amount of feedback control amount for the oscillation control Means for detecting the contact between the tip of the probe and the measurement object from the change and setting the measurement position; means for outputting a confirmation signal when the probe is pushed into the measurement object after detecting the contact; and the confirmation And a means for determining a correct contact detection when a signal is obtained .

共振センサを使った測定の目的は、スタイラス２２が測定対象１０の表面に接触したその瞬間での座標位置を求めることにある。この本来の目的を達成するには、非接触の定常状態にあった検出信号が、接触により過渡状態に突入するその瞬間を捉えることでも可能な筈である。非接触状態にあるスタイラス２２は、共振周波数ω0で定常状態にある。ス
タイラス２２が測定対象１０の表面に接触すると、共振周波数がω0＋Δωへ変化する。
この共振周波数の変化に追従していく制御回路を考えると、追従のためのフィードバック制御量（以下、単に制御量とも称する）は、図７に示すように、スタイラスが測定対象表面と接触した直後に最大となり、時間経過と共に減少していく。即ち、スタイラス２２−測定対象１０間の相互作用の変化によって起きる共振周波数の変化に追従するためのフィードバック制御量（目標値に対する誤差）は、相互作用変化の発生直後に最大となる（厳密に言うと応答時間のため少し遅延する）。一般に、このようなフィードバック制御量の外乱に対する応答性は、時定数に比べて短く、接触発生検出のためのトリガーとして好ましい特性を持っている。 The purpose of the measurement using the resonance sensor is to obtain the coordinate position at the moment when the stylus 22 contacts the surface of the measurement object 10. In order to achieve this original purpose, it is possible to detect the moment when a detection signal in a non-contact steady state enters a transient state by contact. The stylus 22 in the non-contact state is in a steady state at the resonance frequency ω 0 . When the stylus 22 contacts the surface of the measurement object 10, the resonance frequency changes to ω 0 + Δω.
Considering a control circuit that follows this change in resonance frequency, the feedback control amount for tracking (hereinafter also simply referred to as control amount) is immediately after the stylus contacts the surface to be measured, as shown in FIG. It becomes maximum and decreases with time. That is, the feedback control amount (error with respect to the target value) for following the change in the resonance frequency caused by the change in the interaction between the stylus 22 and the measurement object 10 becomes maximum immediately after the change in the interaction occurs (strictly speaking). And a little delay for response time). In general, the response of the feedback control amount to the disturbance is shorter than the time constant, and has a preferable characteristic as a trigger for detecting contact occurrence.

本発明はこのような点に着目してなされたものである。なお、フィードバック制御量を検出するための手段としては、ＰＬＬ、ＤＤＳ、あるいは適応信号処理等を挙げることができる。 The present invention has been made paying attention to such points. Note that examples of means for detecting the feedback control amount include PLL, DDS, and adaptive signal processing.

本発明によれば、測定に要する時間を短くすることが可能であると同時に、測定子−測定対象間の接触時点を高精度に検出することができるので、共振センサの方向依存性や測定対象材質に起因する測定誤差を極めて小さく抑え込むことが可能となる。又、検出回路の削減が可能で低価格化でき、煩雑な校正測定や補正処理が不要で使い勝手が向上できる。   According to the present invention, the time required for measurement can be shortened, and at the same time, the contact point between the probe and the measurement target can be detected with high accuracy. Measurement errors due to the material can be minimized. In addition, the number of detection circuits can be reduced and the price can be reduced, and complicated calibration measurement and correction processing are not required, and usability can be improved.

以下図面を参照して、本発明の実施形態を詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

共振センサは、接触により出力信号の振幅、位相、周波数が変化する。従って、これら３つの物理量のうちいずれか１つを制御量として採用し、その変化を捉えることで接触位置を検知できる。そこで、出力信号の変化を捉える１つの方法として、適応信号処理を使った本発明の第１実施形態を図８に示す。   In the resonance sensor, the amplitude, phase, and frequency of the output signal change due to contact. Therefore, any one of these three physical quantities is adopted as a control quantity, and the contact position can be detected by capturing the change. Therefore, FIG. 8 shows a first embodiment of the present invention using adaptive signal processing as one method for capturing changes in the output signal.

図８において、共振センサ出力信号２０に追随する回路で、共振センサ出力信号２０の中心周波数ωを周波数検出回路３０で検出する。検出した周波数ωの正弦波を正弦波発生回路４２で発生させ、遅延回路４４、位相シフタ４６、可変増幅器４８、５０、加算器５２を使って、共振センサ出力信号２０に追随する周波数ωの参照信号を生成する。このとき、適応アルゴリズム４０により、参照信号は、共振センサ出力信号２０との差（誤差信号）が最小になるように制御される。   In FIG. 8, the center frequency ω of the resonance sensor output signal 20 is detected by the frequency detection circuit 30 in a circuit that follows the resonance sensor output signal 20. A sine wave of the detected frequency ω is generated by the sine wave generation circuit 42, and the delay ω 44, the phase shifter 46, the variable amplifiers 48 and 50, and the adder 52 are used to reference the frequency ω that follows the resonance sensor output signal 20. Generate a signal. At this time, the reference signal is controlled by the adaptive algorithm 40 so that the difference (error signal) from the resonance sensor output signal 20 is minimized.

このように、共振センサ出力信号２０が、接触により急激にその振幅、周波数、位相を変化させた時、適応アルゴリズム４０によって、誤差信号がゼロになるようにパラメータＡｓ、Ｂｓ、ωｓが制御されることによって、参照信号は、共振センサ出力信号に追従しようとする。このとき、誤差信号は、図７に示したように、スタイラス接触直後に最大となり、徐々にゼロに収束していく。従って、この誤差信号を図７の制御量として利用することで、過渡応答を利用した接触検知が実現できる。   As described above, when the resonance sensor output signal 20 suddenly changes its amplitude, frequency, and phase due to contact, the parameters As, Bs, and ωs are controlled by the adaptive algorithm 40 so that the error signal becomes zero. Thus, the reference signal tries to follow the resonance sensor output signal. At this time, as shown in FIG. 7, the error signal becomes the maximum immediately after touching the stylus and gradually converges to zero. Therefore, by using this error signal as the control amount in FIG. 7, contact detection using a transient response can be realized.

ＰＬＬを使っても同様のことができる。ＰＬＬでは、基準信号と入力信号の位相を比較して、その差に相当する信号を出力とする。そこで、図８での正弦波発生回路４２の出力に相当する信号を基準信号（共振センサの非接触状態での発振周波数は制御できるので、その発振周波数の正弦波発生回路の出力でもよい）とする。ここで、入力信号に共振センサ出力信号２０を使い、非接触状態でロックインし、ＰＬＬ出力を安定（≒０）させる。この状態から、センサの接触により入力信号が変化すると、その瞬間にＰＬＬ出力が大きくなり、同期してくると、またＰＬＬ出力が安定（≒０）になる。従って、このＰＬＬ出力を図７の制御量として使うこともできる。   The same can be done using a PLL. In the PLL, the phases of the reference signal and the input signal are compared, and a signal corresponding to the difference is output. Therefore, a signal corresponding to the output of the sine wave generation circuit 42 in FIG. 8 is a reference signal (the oscillation frequency in the non-contact state of the resonance sensor can be controlled, so the output of the sine wave generation circuit of that oscillation frequency may be used). To do. Here, the resonance sensor output signal 20 is used as an input signal and locked in a non-contact state to stabilize (≈0) the PLL output. From this state, when the input signal changes due to the contact of the sensor, the PLL output increases at that moment, and when the input signal is synchronized, the PLL output becomes stable (≈0). Therefore, this PLL output can also be used as the control amount in FIG.

なお、環境因子の変化のような外乱ノイズには弱いので、外乱ノイズの程度によっては対策を施すことが望ましい。即ち、第１実施形態のように、スタイラス２２が測定対象１０に接触した瞬間を検知するのみでは、スタイラス２２自体の加減速や外乱によって誤検出が発生することがある。そこで、本発明の第２実施形態では、接触の瞬間を検出すると共に、スタイラス２２を測定対象１０に更に押し込んで、振動振幅が所定量減衰した時点で確認信号を検出する。つまり、接触信号検出の後に確認信号を検出できた場合にのみ、正しい接触検出と判定する。   In addition, since it is vulnerable to disturbance noise such as changes in environmental factors, it is desirable to take measures depending on the level of disturbance noise. That is, as in the first embodiment, if only the moment when the stylus 22 contacts the measurement object 10 is detected, erroneous detection may occur due to acceleration / deceleration or disturbance of the stylus 22 itself. Therefore, in the second embodiment of the present invention, the moment of contact is detected, and the stylus 22 is further pushed into the measurement object 10 and the confirmation signal is detected when the vibration amplitude is attenuated by a predetermined amount. That is, it is determined that correct contact is detected only when a confirmation signal can be detected after contact signal detection.

ところが、通常、共振センサにおいては、接触と共に共振条件が変化してしまい、安定な振動を持続することが困難となる。そこで、本実施形態では、接触後に共振条件が変化した後でも、安定な発振を持続できるよう発振制御を行ない、これによって確認信号を安定に検出可能としている。   However, in a resonance sensor, the resonance condition usually changes with contact, and it becomes difficult to maintain stable vibration. Therefore, in this embodiment, even after the resonance condition changes after contact, oscillation control is performed so that stable oscillation can be maintained, and thereby the confirmation signal can be detected stably.

このように、フィードバック制御量の過渡応答を利用して接触検出を行なうことにより、信号検出処理を独立に設ける必要も無い上、高速、高精度、高信頼度の接触検出を行なうことが可能となる。 Thus, by performing contact detection using the transient response of the feedback control amount, it is not necessary to provide signal detection processing independently, and it is possible to perform contact detection with high speed, high accuracy, and high reliability. Become.

なお、前記実施形態においては、振幅を利用していたが、出力信号の周波数や位相を用いても良い。加振手段や検出手段も圧電素子に限定されない。   Although the amplitude is used in the embodiment, the frequency and phase of the output signal may be used. Excitation means and detection means are not limited to piezoelectric elements.

触針による表面測定の原理を比較して示す図Diagram showing the principle of surface measurement with a stylus 本発明で用いる共振センサの測定原理を示す図The figure which shows the measurement principle of the resonance sensor used by this invention 同じくスタイラス−測定対象間距離と検出信号の振幅の関係の例を示す図The figure which similarly shows the example of the relationship between stylus-measurement object distance and the amplitude of a detection signal 同じく検出信号の応答を示す図The figure which also shows the response of the detection signal 同じくスタイラスを測定対象に接触直後から押し込んでいく過程の信号検出状態を示す図The figure which shows the signal detection state of the process in which the stylus is pushed into the measuring object immediately after touching 同じくスタイラス−測定対象間距離と検出信号の振幅の関係の変化の例を示す図The figure which similarly shows the example of the change of the relationship between stylus-measurement object distance and the amplitude of a detection signal 本発明の原理を示す図Diagram showing the principle of the present invention 本発明の第１実施形態の構成を示す図The figure which shows the structure of 1st Embodiment of this invention.

符号の説明Explanation of symbols

１０…測定対象
２０…共振センサ
２２…測定子（スタイラス）
２４…加振用圧電素子
２６…検出用圧電素子
２８…加振回路
３０…検出回路
４０…適応アルゴリズム DESCRIPTION OF SYMBOLS 10 ... Measuring object 20 ... Resonance sensor 22 ... Measuring element (stylus)
24 ... Excitation piezoelectric element 26 ... Detection piezoelectric element 28 ... Excitation circuit 30 ... Detection circuit 40 ... Adaptive algorithm

Claims (2)

加振手段により測定子を長手方向に共振振動させ、検出手段により測定子の共振に応じた出力信号を得て、測定子先端と測定対象との接触を検知するようにした共振センサの測定位置検出方法において、
共振状態の変化に追従させて安定な振動を持続するためのフィードバックによる発振制御を行なうと共に、
該発振制御のためのフィードバック制御量の過渡的な変化から、測定子先端と測定対象との接触を検知して測定位置とする際に、
前記接触を検知した後、測定子が測定対象に押し込まれて確認信号が得られた時に、正しい接触検知と判定することを特徴とする共振センサの測定位置検出方法。 The measurement position of the resonance sensor, in which the probe is resonantly vibrated in the longitudinal direction by the vibration means, the output signal corresponding to the resonance of the probe is obtained by the detection means, and the contact between the probe tip and the measurement object is detected. In the detection method,
While performing oscillation control by feedback to keep the stable vibration by following the change of resonance state,
From the transient change of the feedback control amount for the oscillation control, when detecting the contact between the tip of the probe and the measurement object and setting it as the measurement position ,
A method for detecting a measurement position of a resonance sensor, comprising: determining a correct contact detection when a probe is pushed into an object to be measured and a confirmation signal is obtained after detecting the contact . 加振手段により測定子を長手方向に共振振動させ、検出手段により測定子の共振に応じた出力信号を得て、測定子先端と測定対象との接触を検知するようにした共振センサの測定位置検出装置において、
共振状態の変化に追従させて安定な振動を持続するためのフィードバックによる発振制御を行なう発振制御手段と、
該発振制御のためのフィードバック制御量の過渡的な変化から、測定子先端と測定対象との接触を検知して測定位置とする手段と、
前記接触を検知した後、測定子が測定対象に押し込まれた時に確認信号を出力する手段と、
該確認信号が得られた時に、正しい接触検知と判定する手段と、
を備えたことを特徴とする共振センサの測定位置検出装置。 The measurement position of the resonance sensor, in which the probe is resonantly vibrated in the longitudinal direction by the vibration means, the output signal corresponding to the resonance of the probe is obtained by the detection means, and the contact between the probe tip and the measurement object is detected. In the detection device,
Oscillation control means for performing oscillation control by feedback to keep the stable vibration by following the change of the resonance state;
Means for detecting the contact between the tip of the probe and the measurement object from the transient change in the feedback control amount for the oscillation control, and setting the measurement position;
Means for outputting a confirmation signal when the probe is pushed into the measurement object after detecting the contact;
Means for determining correct contact detection when the confirmation signal is obtained;
A measurement position detecting device for a resonance sensor, comprising:
JP2007202180A 2007-08-02 2007-08-02 Method and apparatus for detecting measurement position of resonance sensor Expired - Fee Related JP5032235B2 (en)

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