JP2008070159A - Scanning range finder - Google Patents
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Abstract
Description
本発明は、パルス状の測定光を出力する投光部と、前記投光部から出力された測定光を測定対象空間に向けて走査する走査部と、前記測定対象空間に存在する測定対象物からの反射光を検出する受光部を備え、前記受光部で検出された前記反射光に基づいて前記測定対象物までの距離を測定するTOF(Time of Flight)方式による走査式測距装置に関する。 The present invention provides a light projecting unit that outputs pulsed measurement light, a scanning unit that scans the measurement light output from the light projecting unit toward the measurement target space, and a measurement target that exists in the measurement target space. The present invention relates to a scanning distance measuring device using a TOF (Time of Flight) system that includes a light receiving unit that detects reflected light from a light source and measures a distance to the measurement object based on the reflected light detected by the light receiving unit.
この種の走査式測距装置は、ロボットや無人搬送車の視覚センサ、或いは、ドアの開閉センサや監視領域への侵入者の有無を検出する監視センサ、さらには、危険な装置に人や物が近づくのを検出し、機械を安全に停止する安全センサ等に利用され、発光ダイオードやレーザダイオード等の光源を備えてパルス状の測定光を出力する投光部と、測定光を測定対象空間に向けて回転走査する走査部と、走査された測定光が測定対象物で反射した反射光を光電変換素子により検出する受光部と、前記投光部から出力される測定光の出力タイミングと、測定対象物で反射した反射光の検出タイミングの時間差に基づいて物体までの距離を演算する演算部を備えて構成されている。 This type of scanning distance measuring device is a visual sensor of a robot or an automated guided vehicle, a door opening / closing sensor, a monitoring sensor for detecting the presence or absence of an intruder into a monitoring area, and a person or object in a dangerous device. Is used as a safety sensor that detects the approach of the machine and safely stops the machine, and includes a light emitting unit that outputs a pulsed measurement light with a light source such as a light emitting diode or a laser diode, and the measurement light in the measurement target space. A scanning unit that rotates and scans toward the surface, a light receiving unit that detects reflected light reflected by the measurement object scanned by the photoelectric conversion element, and an output timing of the measurement light output from the light projecting unit, An arithmetic unit that calculates the distance to the object based on the time difference in the detection timing of the reflected light reflected by the measurement object is provided.
特許文献1に記載されているように、一般的には、前記演算部は、前記光源に対する駆動信号の立ち上りエッジから前記受光部により検出される反射光の検出タイミング迄の遅延時間を検出するカウンタ回路を備えた信号処理回路で構成されているが、光源の発光特性や受光部に設けた光電変換素子の受光特性等の部品間のばらつきや経時変化による変動に起因して算出される距離に誤差が生じるという問題があった。 As described in Patent Document 1, generally, the calculation unit is a counter that detects a delay time from a rising edge of a driving signal for the light source to a detection timing of reflected light detected by the light receiving unit. Although it is composed of a signal processing circuit with a circuit, the distance is calculated due to variations between components such as the light emission characteristics of the light source and the light reception characteristics of the photoelectric conversion element provided in the light receiving section, and variations due to changes over time. There was a problem that an error occurred.
測距精度の向上を図るべく、パルス状の測定光と反射光の双方を同一の受光部で検出して、時間的に前後して検出される双方の検出信号から時間差を算出する信号処理回路を備えることにより、測定系の部品ばらつきや経年変化による誤差を吸収することが考えられるが、このような構成を採用すると、装置の近傍に測定対象物が位置する場合には、受光部で検出される測定光と反射光が重なるために正確に計測できないという本質的問題が内在している。 In order to improve distance measurement accuracy, a signal processing circuit that detects both pulsed measurement light and reflected light with the same light receiving unit and calculates a time difference from both detection signals detected before and after time It is conceivable to absorb errors due to component variations and aging of the measurement system, but if such a configuration is used, the light receiving unit detects when the measurement object is located near the device. The inherent problem is that accurate measurement cannot be performed because the measured light and reflected light overlap.
そこで、特許文献2には、走査部を構成する回転体が基準回転位置にあるときに投光部と受光部とを一定の光路長さで光学的に結合させる基準機構を設け、回転体が基準回転位置にきたときの演算出力、つまり、投光部への駆動信号と基準機構を介して受光部で検出される測定光との時間差に基づいて基準距離を演算し、投光部への駆動信号と受光部で検出される反射光との時間差に基づいて演算される距離を前記基準距離で補正する信号処理回路を備えた走査式測距装置が提案されている。
しかし、上述の特許文献2に記載された走査式測距装置では、前記回転体が基準回転位置にあるときには測定対象空間に測定光を出力できないため、死角が生じるという問題があり、当該死角となる測定対象空間を測定するためにさらに別の走査式測距装置を設置しなければならないという問題があった。 However, in the scanning distance measuring device described in Patent Document 2 described above, there is a problem that a blind spot occurs because the measurement light cannot be output to the measurement target space when the rotating body is at the reference rotational position. In order to measure the space to be measured, another scanning range finder has to be installed.
また、前記回転体が基準回転位置にあるときに得られる基準距離に基づいて補正が施されるため、基準距離の検出時や反射光の検出時に、光源の発光遅延や受光部の応答遅延等の変動が生じると、その走査時における検出距離の精度が低下するという問題もあった。 Further, since correction is performed based on the reference distance obtained when the rotating body is at the reference rotation position, the light emission delay of the light source, the response delay of the light receiving unit, etc. when detecting the reference distance or detecting the reflected light When this variation occurs, there is a problem that the accuracy of the detection distance at the time of scanning decreases.
本発明の目的は、上述した問題点に鑑み、測定対象空間に死角が生じることなく、周囲360度に亘って高精度な距離測定を実現し得る走査式測距装置を提供する点にある。 In view of the above-described problems, an object of the present invention is to provide a scanning distance measuring device capable of realizing highly accurate distance measurement over 360 degrees without causing a blind spot in a measurement target space.
上述の目的を達成するため、本発明による走査式測距装置の第一の特徴構成は、特許請求の範囲の書類の請求項1に記載した通り、パルス状の測定光を出力する投光部と、前記投光部から出力された測定光を測定対象空間に向けて走査する走査部と、前記測定対象空間に存在する測定対象物からの反射光を検出する受光部を備え、前記受光部で検出された前記反射光に基づいて前記測定対象物までの距離を測定する走査式測距装置であって、前記測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路を備えると共に、前記測定光の出力タイミングに同期して前記受光部により検出される前記基準光と前記反射光の検出時間差に基づいて前記測定対象物までの距離を算出する演算部を備えている点にある。 In order to achieve the above-mentioned object, the first characteristic configuration of the scanning distance measuring device according to the present invention is the light projecting unit for outputting the pulsed measurement light as described in claim 1 of the claims. A scanning unit that scans the measurement light output from the light projecting unit toward the measurement target space, and a light receiving unit that detects reflected light from the measurement target existing in the measurement target space, the light receiving unit A scanning distance measuring device that measures the distance to the measurement object based on the reflected light detected in Step 1, wherein a part of the measurement light is used as a reference light and is guided to the light receiving unit with a constant optical path length. An optical path, and a calculation unit that calculates a distance to the measurement object based on a detection time difference between the reference light and the reflected light detected by the light receiving unit in synchronization with an output timing of the measurement light. There is in point.
上述の構成によれば、パルス状の測定光が出力される度に、その一部が基準光として導光路を介して受光部で検出されるとともに、その後に測定対象物からの反射光が受光部により検出されるようになる。そして演算部によりそれらの検出信号の時間差が算出されるときに、光源の発光遅延や受光部の応答遅延等の変動の影響も相殺されるため、測定対象物までの距離を精度良く算出することができるようになるのである。このような走査式測距装置によれば、走査部の走査角度にかかわらずパルス状の測定光の出力タイミングに同期して少なくとも基準光が常に検出されるようになるため、死角が生じることなく、検出対象空間の全範囲に亘り測定対象物迄の距離を精度良く検出することができるのである。 According to the configuration described above, every time pulsed measurement light is output, a part of the measurement light is detected as a reference light by the light receiving section through the light guide, and then the reflected light from the measurement object is received. Is detected by the unit. And when the time difference between these detection signals is calculated by the calculation unit, the influence of fluctuations such as the light emission delay of the light source and the response delay of the light receiving unit is offset, so the distance to the measurement object can be calculated accurately. Will be able to. According to such a scanning distance measuring device, at least the reference light is always detected in synchronism with the output timing of the pulsed measurement light regardless of the scanning angle of the scanning unit, so that a blind spot does not occur. Thus, the distance to the measurement object can be accurately detected over the entire range of the detection object space.
同第二の特徴構成は、同請求項2に記載した通り、上述の第一特徴構成に加えて、前記走査部は、前記測定光を前記測定対象空間に向けて反射する投光ミラーと、前記測定対象物からの反射光を前記受光部に向けて反射する受光ミラーと、前記投光ミラー及び前記受光ミラーを前記投光部と前記受光部を結ぶ軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記回転機構により回転し、前記投光ミラーで反射した前記測定光の一部を前記受光ミラーに導く導光部材を備えて構成されている点にある。 In addition to the first feature configuration described above, the second feature configuration is the light projection mirror that reflects the measurement light toward the measurement target space, in addition to the first feature configuration described above. A light receiving mirror that reflects reflected light from the measurement object toward the light receiving unit, and a rotation mechanism that rotates the light projecting mirror and the light receiving mirror about an axis that connects the light projecting unit and the light receiving unit. The reference optical path is configured to include a light guide member that is rotated by the rotation mechanism and guides a part of the measurement light reflected by the light projecting mirror to the light receiving mirror.
上述の構成によれば、投光部から出力された測定光の一部は、投光ミラーで反射された後、導光部材により受光ミラーへと導かれ、受光部で受光される。このようにして、測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路が形成される。このような導光部材は投光ミラー及び受光ミラーと一体に回転するので、走査部による走査角度にかかわらず常に基準光路が形成されることとなる。 According to the above configuration, part of the measurement light output from the light projecting unit is reflected by the light projecting mirror, then guided to the light receiving mirror by the light guide member, and received by the light receiving unit. In this manner, a reference optical path is formed that guides a part of the measurement light to the light receiving unit with a constant optical path length using the reference light as a reference light. Since such a light guide member rotates integrally with the light projecting mirror and the light receiving mirror, a reference optical path is always formed regardless of the scanning angle by the scanning unit.
同第三の特徴構成は、同請求項3に記載した通り、上述の第一特徴構成に加えて、前記走査部は、前記測定光を前記測定対象空間に向けて反射する投光ミラーと、前記測定対象物からの反射光を前記受光部に向けて反射する受光ミラーと、前記投光ミラー及び前記受光ミラーを前記投光部と前記受光部を結ぶ軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記回転機構による回転軸心と同軸心に配置され、前記投光ミラーで反射した前記測定光の一部を前記受光ミラーに導く円環状の反射部材を備えて構成されている点にある。 In addition to the first feature configuration described above, the third feature configuration is the light projection mirror that reflects the measurement light toward the measurement target space, in addition to the first feature configuration described above. A light receiving mirror that reflects reflected light from the measurement object toward the light receiving unit, and a rotation mechanism that rotates the light projecting mirror and the light receiving mirror about an axis that connects the light projecting unit and the light receiving unit. The reference optical path includes an annular reflecting member that is arranged coaxially with the rotation axis of the rotation mechanism and guides a part of the measurement light reflected by the light projecting mirror to the light receiving mirror. It is in the point which is comprised.
上述の構成によれば、投光部から出力された測定光の一部は、投光ミラーで反射された後、走査部の周囲を囲むように配置された円環状の反射部材によって受光ミラーに向けて反射されて受光部に導かれる。このような反射部材は走査部の周囲を囲むように円環状に配置されているので、走査部による走査角度にかかわらず常に基準光路が形成されることとなる。 According to the above-described configuration, part of the measurement light output from the light projecting unit is reflected by the light projecting mirror, and then is reflected on the light receiving mirror by the annular reflecting member disposed so as to surround the scanning unit. The light is reflected toward the light receiving unit. Since such reflecting members are arranged in an annular shape so as to surround the periphery of the scanning unit, a reference optical path is always formed regardless of the scanning angle by the scanning unit.
同第四の特徴構成は、同請求項4に記載した通り、上述の第一特徴構成に加えて、前記走査部は、前記測定光を前記測定対象空間に向けて反射する投光ミラーと、前記測定対象物からの反射光を前記受光部に向けて反射する受光ミラーと、前記投光ミラー及び前記受光ミラーを前記投光部と前記受光部を結ぶ軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記回転機構による回転軸心に沿って前記投光部から前記受光部に前記測定光の一部を導くように構成されている点にある。 In the fourth feature configuration, as described in claim 4, in addition to the first feature configuration described above, the scanning unit includes a light projection mirror that reflects the measurement light toward the measurement target space, and A light receiving mirror that reflects reflected light from the measurement object toward the light receiving unit, and a rotation mechanism that rotates the light projecting mirror and the light receiving mirror about an axis that connects the light projecting unit and the light receiving unit. And the reference optical path is configured to guide a part of the measurement light from the light projecting unit to the light receiving unit along a rotation axis of the rotation mechanism.
上述の構成によれば、投光部から出力された測定光の一部が、投光ミラーで反射されることなく、回転軸心に沿った基準光路により受光部に導かれる。このような基準光路は、前記投光ミラー及び前記受光ミラーに前記軸心に沿った貫通孔を形成することにより容易に構成でき、また、前記投光ミラー及び前記受光ミラーに形成される鏡面のうち前記軸心と交差する部位を非鏡面である透過面に、つまり測定光を透過させるように構成することにより容易に構成することができる。 According to the above configuration, part of the measurement light output from the light projecting unit is guided to the light receiving unit by the reference optical path along the rotation axis without being reflected by the light projecting mirror. Such a reference optical path can be easily configured by forming a through-hole along the axis in the light projecting mirror and the light receiving mirror, and a mirror surface formed in the light projecting mirror and the light receiving mirror. Of these, the portion intersecting with the axis can be easily configured by transmitting the measurement light to the non-mirror surface of the transmission surface.
同第五の特徴構成は、同請求項5に記載した通り、上述の第一特徴構成に加えて、前記測定光を前記走査部に向けて反射するミラーをさらに備え、前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記測定光の一部を前記ミラーを介さずに前記受光部に導く導光部材を備えて構成されている点にある。 In the fifth feature configuration, in addition to the first feature configuration described above, the fifth feature configuration further includes a mirror that reflects the measurement light toward the scanning unit. A light projecting / receiving mirror that reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; The reference optical path is configured to include a light guide member that guides a part of the measurement light to the light receiving unit without passing through the mirror.
上述の構成によれば、投光部と受光部とを投受光ミラーに対して同一側に配置する場合に、投光部から出力される測定光の一部を走査部を介することなく導光部材によって受光部に導くことにより容易に基準光路を形成することができるようになる。 According to the above configuration, when the light projecting unit and the light receiving unit are arranged on the same side with respect to the light projecting / receiving mirror, a part of the measurement light output from the light projecting unit is guided without passing through the scanning unit. The reference optical path can be easily formed by guiding the light receiving unit by the member.
同第六の特徴構成は、同請求項6に記載した通り、上述の第一特徴構成に加えて、前記測定光を前記走査部に向けて反射するミラーをさらに備え、前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記回転機構による回転軸心と同軸心に配置され、前記投受光ミラーで反射された前記測定光の一部を前記投受光ミラーに導く円環状の反射部材を備えて構成されている点にある。 In addition to the first feature configuration described above, the sixth feature configuration further includes a mirror that reflects the measurement light toward the scanning unit, and the scanning unit includes: A light projecting / receiving mirror that reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; The reference optical path is arranged coaxially with the rotation axis of the rotation mechanism, and a part of the measurement light reflected by the light projecting / receiving mirror is transmitted / received. It is in the point comprised with the annular | circular shaped reflection member guide | induced to a mirror.
上述の構成によれば、投光部と受光部とを投受光ミラーに対して同一側に配置する場合に、投光部から出力された測定光が投受光ミラーに導かれ、投受光ミラーで走査のために反射された測定光の一部が、走査部の周囲を囲むように配置された円環状の反射部材により再度投受光ミラーに向けて反射され、その後に受光部で受光されるように基準光路が形成される。反射部材は、走査部の周囲を囲むように円環状に配置されているため、走査領域の全域に亘って基準光路が形成されるようになる。 According to the above configuration, when the light projecting unit and the light receiving unit are arranged on the same side with respect to the light projecting / receiving mirror, the measurement light output from the light projecting unit is guided to the light projecting / receiving mirror, A part of the measurement light reflected for scanning is reflected again toward the light projecting / receiving mirror by the annular reflecting member arranged so as to surround the periphery of the scanning unit, and then received by the light receiving unit. A reference optical path is formed. Since the reflecting member is arranged in an annular shape so as to surround the periphery of the scanning unit, a reference optical path is formed over the entire scanning region.
同第七の特徴構成は、同請求項7に記載した通り、上述の第一特徴構成に加えて、前記測定光を前記走査部に向けて反射するミラーをさらに備え、前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、前記基準光路は、前記回転機構により回転し、前記投受光ミラーで反射された前記測定光の一部を前記投受光ミラーに向けて反射する反射部材を備えて構成されている点にある。 The seventh characteristic configuration further includes a mirror that reflects the measurement light toward the scanning unit, in addition to the first characteristic configuration described above, as described in claim 7, A light projecting / receiving mirror that reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; A reflection mechanism configured to rotate around the center, and the reference optical path is rotated by the rotation mechanism and reflects a part of the measurement light reflected by the light projecting / receiving mirror toward the light projecting / receiving mirror. In the point comprised with the member.
上述の構成によれば、投光部と受光部とを投受光ミラーに対して同一側に配置する場合に、投光部から出力された測定光が投受光ミラーに導かれ、投受光ミラーで走査のために反射された測定光の一部が、回転機構により回転する反射部材により再度投受光ミラーに向けて反射され、その後に受光部で受光されるように基準光路が形成される。反射部材は投受光ミラーと一体に回転するため、走査領域の全域に亘って基準光路が形成されるようになる。 According to the above configuration, when the light projecting unit and the light receiving unit are arranged on the same side with respect to the light projecting / receiving mirror, the measurement light output from the light projecting unit is guided to the light projecting / receiving mirror, A part of the measurement light reflected for scanning is reflected again toward the light projecting / receiving mirror by the reflecting member rotated by the rotating mechanism, and then a reference optical path is formed so as to be received by the light receiving unit. Since the reflecting member rotates integrally with the light projecting / receiving mirror, a reference optical path is formed over the entire scanning region.
同第八の特徴構成は、同請求項8に記載した通り、パルス状の測定光を出力する投光部と、前記投光部から出力された測定光を測定対象空間に向けて走査する走査部と、前記測定対象空間に存在する測定対象物からの反射光を検出する受光部を備え、前記受光部で検出された前記反射光に基づいて測定対象物までの距離を測定する走査式測距装置であって、前記測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路を備えると共に、前記測定光の出力タイミングに同期して前記受光部により検出される前記基準光と前記反射光の検出時間差に基づいて測定対象物までの距離を算出する演算部を備え、前記受光部で検出される前記基準光の最大信号レベルが所定の第一閾値以下となるように前記基準光の光量が予め調整され、前記反射光と識別可能に構成されている点にある。 According to the eighth feature of the invention, as described in claim 8, a light projecting unit that outputs pulsed measurement light, and a scan that scans the measurement light output from the light projecting unit toward the measurement target space And a light-receiving unit that detects reflected light from the measurement object existing in the measurement object space, and measures the distance to the measurement object based on the reflected light detected by the light-receiving unit. A distance device comprising a reference optical path that guides a part of the measurement light as a reference light to the light receiving unit with a constant optical path length, and is detected by the light receiving unit in synchronization with an output timing of the measurement light An arithmetic unit that calculates a distance to the measurement object based on a detection time difference between the reference light and the reflected light is provided so that the maximum signal level of the reference light detected by the light receiving unit is equal to or lower than a predetermined first threshold value. The amount of the reference light is adjusted in advance, In that it is identifiable structure as serial reflected light.
上述の構成によれば、基準光の最大信号レベルが所定の第一閾値、つまり、測定対象物からの反射光の想定最大信号レベルより低い値以下になるように予め調整されるので、測定光の出力タイミングに同期した所定のタイミングにおいて受光部で検出される信号レベルが第一閾値より高いときには、走査式測距装置の近傍に測定対象物が位置すると判断することができ、誤った演算を行なうことなく、適切に対応することができるようになるのである。 According to the above-described configuration, the reference light is adjusted in advance so that the maximum signal level of the reference light is lower than the predetermined first threshold, that is, a value lower than the assumed maximum signal level of the reflected light from the measurement object. When the signal level detected by the light receiving unit at a predetermined timing synchronized with the output timing is higher than the first threshold, it can be determined that the measurement object is located in the vicinity of the scanning distance measuring device, and erroneous calculation is performed. You can respond appropriately without doing it.
同第九の特徴構成は、同請求項9に記載した通り、上述の第八特徴構成に加えて、前記受光部で検出される前記基準光の信号レベルが前記第一閾値以下のときに、今回の基準光に基づいて得られる特性データを記憶する記憶部を備え、前記演算部は、前記基準光の信号レベルが前記第一閾値より大となるときに、前記記憶部に記憶された過去の特性データに基づいて得られる前記測定光の出力タイミングから前記基準光が検出されるまでの基準光遅延時間と、前記測定光の出力タイミングから前記反射光が検出されるまでの反射光遅延時間との時間差に基づいて前記測定対象物までの距離を算出する点にある。 In the ninth feature configuration, as described in claim 9, in addition to the eighth feature configuration described above, when the signal level of the reference light detected by the light receiving unit is equal to or lower than the first threshold value, A storage unit that stores characteristic data obtained based on the current reference light is provided, and the arithmetic unit stores past data stored in the storage unit when the signal level of the reference light is greater than the first threshold value. A reference light delay time from the measurement light output timing obtained from the measurement data to the detection of the reference light, and a reflected light delay time from the measurement light output timing to the detection of the reflected light The distance to the measurement object is calculated on the basis of the time difference.
上述の構成によれば、走査式測距装置の近傍に測定対象物が位置すると判断されたときには、近傍に測定対象物が存在しないと判断された過去において記憶部に記憶された基準光により得られる特性データに基づいて、前記測定光の出力タイミングから前記基準光が検出されるまでの基準光遅延時間を取得し、その基準光遅延時間を基準として、測定対象物までの距離を算出するのである。従って、装置の近傍に測定対象物が位置するときであっても、正確に測距することができるようになる。 According to the above configuration, when it is determined that the measurement object is located in the vicinity of the scanning distance measuring device, it is obtained from the reference light stored in the storage unit in the past when it is determined that the measurement object does not exist in the vicinity. Based on the obtained characteristic data, the reference light delay time until the reference light is detected from the output timing of the measurement light is obtained, and the distance to the measurement object is calculated based on the reference light delay time. is there. Therefore, even when the measurement object is located in the vicinity of the apparatus, the distance can be accurately measured.
同第十の特徴構成は、同請求項10に記載した通り、上述の第九特徴構成に加えて、前記受光部で検出される前記基準光の信号レベルが前記第一閾値以下のときに前記信号波形の累積平均波形を記憶する記憶部を備え、前記演算部は、前記基準光の信号レベルが前記第一閾値より大となるときに、当該信号波形から前記記憶部に記憶された累積平均波形を減算した信号を前記反射光として求める点にある。 According to the tenth feature configuration, in addition to the ninth feature configuration described above, when the signal level of the reference light detected by the light receiving unit is equal to or lower than the first threshold value, A storage unit that stores a cumulative average waveform of the signal waveform, and the arithmetic unit stores a cumulative average stored in the storage unit from the signal waveform when the signal level of the reference light is greater than the first threshold value. The signal is obtained by subtracting the waveform as the reflected light.
上述の構成によれば、走査式測距装置の近傍に測定対象物が位置すると判断されたときには、そのときの信号波形、つまり基準光と反射光が重畳した信号波形から、近傍に測定対象物が存在しないと判断された過去において記憶部に記憶された基準光の累積平均波形を減算することにより、正確な反射光に対応する信号波形が得られるようになる。そのような反射光の検出信号に対して上述の第九特徴構成による演算を行なうことにより、より正確に測距することができるようになる。 According to the above-described configuration, when it is determined that the measurement object is located in the vicinity of the scanning distance measuring device, the measurement object is detected from the signal waveform at that time, that is, the signal waveform in which the reference light and the reflected light are superimposed. By subtracting the cumulative average waveform of the reference light stored in the storage unit in the past when it is determined that there is no signal, an accurate signal waveform corresponding to the reflected light can be obtained. By performing the calculation according to the above-described ninth feature configuration on the detection signal of such reflected light, the distance can be measured more accurately.
同第十一の特徴構成は、同請求項11に記載した通り、上述の第九または第十の特徴構成に加えて、前記特性データが、基準光の信号波形、信号波形の累積加算波形、基準光遅延時間、基準光遅延時間の平均遅延時間の何れかである点にある。 In the eleventh feature configuration, in addition to the ninth or tenth feature configuration described above, the characteristic data includes a signal waveform of a reference light, a cumulative addition waveform of a signal waveform, This is either the reference light delay time or the average delay time of the reference light delay time.
記憶部に記憶される特性データとして正規に取得された基準光の信号波形を採用する場合には、ほぼ正確な基準光遅延時間を算出することができ、過去の信号波形との累積加算波形を採用する場合には、第一閾値の近傍の低い信号レベルであっても十分なレベルに嵩上げされるので、ノイズの影響を受けない精度の高い基準光遅延時間を算出することができ、基準光遅延時間を採用する場合には、基準光遅延時間を算出する演算時間が省略でき、過去の基準光遅延時間との平均遅延時間を採用する場合には、誤差が吸収された精度の高い基準光遅延時間が得られるようになる。 When the signal waveform of the reference light acquired normally as the characteristic data stored in the storage unit is adopted, an almost accurate reference light delay time can be calculated, and the cumulative addition waveform with the past signal waveform can be calculated. When adopted, even a low signal level in the vicinity of the first threshold is raised to a sufficient level, so that a highly accurate reference light delay time that is not affected by noise can be calculated. When the delay time is adopted, the calculation time for calculating the reference light delay time can be omitted, and when the average delay time with the past reference light delay time is adopted, the reference light with high accuracy in which the error is absorbed is used. Delay time can be obtained.
同第十二の特徴構成は、同請求項12に記載した通り、上述の第八から第十の何れかの特徴構成に加えて、前記受光部で検出される前記基準光の信号レベルが前記第一閾値以下のときに、今回の基準光と過去の信号波形との累積加算波形、今回の基準光と過去の信号波形との平均波形、または、今回の基準光遅延時間と過去の基準光遅延時間との平均遅延時間を記憶する記憶部を備え、前記演算部は、前記記憶部に記憶された累積加算波形、平均波形、または、平均遅延時間の何れかに基づいて得られる前記測定光の出力タイミングから前記基準光が検出されるまでの基準光遅延時間と、前記測定光の出力タイミングから前記反射光が検出されるまでの反射光遅延時間との時間差に基づいて前記測定対象物までの距離を算出する点にある。 In the twelfth feature configuration, as described in claim 12, in addition to any of the eighth to tenth feature configurations described above, the signal level of the reference light detected by the light receiving unit is Cumulative addition waveform of current reference light and past signal waveform, average waveform of current reference light and past signal waveform, or current reference light delay time and past reference light when below first threshold A storage unit that stores an average delay time with respect to the delay time, and the calculation unit is configured to obtain the measurement light obtained based on any of the cumulative addition waveform, the average waveform, or the average delay time stored in the storage unit To the measurement object based on a time difference between a reference light delay time from the output timing of the reference light until the reference light is detected and a reflected light delay time from the output timing of the measurement light to the detection of the reflected light. The point is to calculate the distance.
記憶部に記憶される特性データとして過去の信号波形との累積加算波形を採用する場合には、第一閾値の近傍の低い信号レベルであっても十分なレベルに嵩上げされるので、ノイズの影響を受けない精度の高い基準光遅延時間を算出することができ、今回の基準光と過去の信号波形との平均波形を採用する場合には、ノイズが吸収されて精度の高い基準光遅延時間が得られ、過去の基準光遅延時間との平均遅延時間を採用する場合には、誤差が吸収された精度の高い基準光遅延時間が得られるようになる。 When the cumulative addition waveform with the past signal waveform is adopted as the characteristic data stored in the storage unit, even a low signal level in the vicinity of the first threshold is raised to a sufficient level. If the average waveform of the current reference light and the past signal waveform is used, the noise is absorbed and the reference light delay time is accurate. When the average delay time with the past reference light delay time is employed, a highly accurate reference light delay time in which the error is absorbed can be obtained.
同第十三の特徴構成は、同請求項13に記載した通り、上述の第八から第十二の何れかの特徴構成に加えて、前記受光部で検出される前記基準光の信号レベルが前記第一閾値より低く設定された第二閾値より小となるときに、故障と検出する自己診断部を備えている点にある。 In the thirteenth feature configuration, as described in claim 13, in addition to any of the eighth to twelfth feature configurations described above, the signal level of the reference light detected by the light receiving unit is A self-diagnosis unit that detects a failure when it becomes smaller than a second threshold value set lower than the first threshold value is provided.
上述の構成によれば、受光部で検出される基準光の信号レベルが第二閾値より小であるときに、投光部または受光部を構成する光源や受光素子等の部品または光学系に何らかの支障を来たしていると判断することができ、誤った出力により当該走査式測距装置が組み込まれたシステムが誤動作することを未然に回避することができるようになる。 According to the above-described configuration, when the signal level of the reference light detected by the light receiving unit is lower than the second threshold value, the light source, the light receiving element, or the like constituting the light projecting unit or the light receiving unit or any optical system It can be determined that a problem has occurred, and it is possible to prevent malfunction of a system in which the scanning distance measuring device is incorporated due to erroneous output.
以上説明した通り、本発明によれば、測定対象空間に死角が生じることなく、周囲360度に亘って高精度な距離測定を実現し得る走査式測距装置を提供することができるようになった。 As described above, according to the present invention, it is possible to provide a scanning distance measuring device that can realize highly accurate distance measurement over 360 degrees without causing a blind spot in the measurement target space. It was.
以下、本発明による走査式測距装置の実施形態を図面に基づいて説明する。 Embodiments of a scanning distance measuring apparatus according to the present invention will be described below with reference to the drawings.
図1は、本発明の第1の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。同図に示すように、この走査式測距装置1は、ハウジング2を備えると共に、このハウジング2の内部に、投光部3と、走査部4と、受光部5と、基準光路を構成する導光部材としての光ファイバ6とを主たる構成要素として備えている。 FIG. 1 is a schematic longitudinal sectional view showing the overall configuration of the scanning distance measuring apparatus according to the first embodiment of the present invention. As shown in the figure, the scanning distance measuring device 1 includes a housing 2, and a light projecting unit 3, a scanning unit 4, a light receiving unit 5, and a reference optical path are formed inside the housing 2. An optical fiber 6 as a light guide member is provided as a main component.
ハウジング2は、図中の上下方向の両端が閉じられた円筒状を呈し、その周壁部2aの全周に亘って上下方向に一定の幅を有する円環状の透光窓2a1が形成され、この透光窓2を介して、後述する投光部3から出力されるパルス状の測定光と、物体で反射して受光部5に至る反射光とが往来可能となっている。 The housing 2 has a cylindrical shape in which both ends in the vertical direction in the figure are closed, and an annular light-transmitting window 2a1 having a constant width in the vertical direction is formed over the entire circumference of the peripheral wall portion 2a. Via the light transmitting window 2, pulsed measurement light output from a light projecting unit 3 to be described later and reflected light that is reflected by an object and reaches the light receiving unit 5 can come and go.
投光部3は、例えば発光ダイオードや半導体レーザ等の発光素子と、発光素子の駆動回路を備えて構成され、発光素子は図中の下向きにパルス状の測定光を出力するように配置されている。この投光部3から下向きに出力された測定光が通る投光入射光路L1上には、光のビーム径を一定にする光学レンズ7が配置されている。 The light projecting unit 3 includes a light emitting element such as a light emitting diode or a semiconductor laser and a drive circuit for the light emitting element, and the light emitting element is arranged to output pulsed measurement light downward in the figure. Yes. An optical lens 7 for making the beam diameter of the light constant is disposed on the light incident optical path L1 through which the measurement light output downward from the light projecting unit 3 passes.
走査部4は、投光部3から出力された測定光をハウジング2の透光窓2a1を介して外部の測定対象空間に走査するもので、本実施形態では、回転体8と、投光ミラー9と、受光ミラー10と、回転機構としてのモータ11とから構成されている。回転体8は、筒状の周壁部8aと、周壁部8aの上端を塞ぐ天板部8bとから構成されている。周壁部8aの下端部は縮径され、その内周面に軸受12を介して中空軸13が挿入されており、この中空軸13によって回転体8が投光入射光路L1の光軸を中心として回転可能に支承されている。 The scanning unit 4 scans the measurement light output from the light projecting unit 3 to the external measurement target space via the light transmission window 2a1 of the housing 2, and in this embodiment, the rotating body 8 and the light projecting mirror are used. 9, a light receiving mirror 10, and a motor 11 as a rotation mechanism. The rotating body 8 includes a cylindrical peripheral wall portion 8a and a top plate portion 8b that closes the upper end of the peripheral wall portion 8a. The lower end portion of the peripheral wall portion 8a is reduced in diameter, and a hollow shaft 13 is inserted into its inner peripheral surface via a bearing 12, and the rotating body 8 is centered on the optical axis of the light incident light path L1 by the hollow shaft 13. It is supported so that it can rotate.
この回転体8を回転駆動するモータ11は、固定子側にコイル11aを、回転子側にマグネット11bをそれぞれ備え、マグネット11bが、回転体8の周壁部8aの下端部の外周面に取り付けられ、コイル11aとの相互作用により、回転体8が、投光入射光路L1の光軸を回転軸として回転するように構成されている。 The motor 11 that rotationally drives the rotating body 8 includes a coil 11 a on the stator side and a magnet 11 b on the rotor side, and the magnet 11 b is attached to the outer peripheral surface of the lower end portion of the peripheral wall portion 8 a of the rotating body 8. The rotating body 8 is configured to rotate about the optical axis of the light incident light path L1 by the interaction with the coil 11a.
回転体8の天板部8bの上下面には、回転軸上に、投光ミラー9と、受光ミラー10とがそれぞれ傾斜姿勢で取り付けられ、投光部3から出射された測定光が、投光入射光路L1によって投光ミラー9に入射した後、反射して投光出射光路L2に導かれるとともに、ハウジング2の外方に形成される測定対象空間である走査領域内に存在する物体、つまり測定対象物からの反射光が、受光入射光路L3によって受光ミラー10に入射した後、反射して受光出射光路L4に導かれる。 On the top and bottom surfaces of the top plate portion 8b of the rotator 8, the light projection mirror 9 and the light receiving mirror 10 are respectively mounted in an inclined posture on the rotation axis, and the measurement light emitted from the light projection portion 3 is projected. After being incident on the light projection mirror 9 by the light incident optical path L1, the object is reflected and guided to the light projecting and exiting optical path L2, and is present in the scanning region which is a measurement target space formed outside the housing 2, That is, the reflected light from the measurement object is incident on the light receiving mirror 10 through the light receiving incident light path L3 and then reflected and guided to the light receiving and emitting light path L4.
即ち、走査部4は、パルス状の測定光を測定対象空間に向けて反射する投光ミラー9と、測定対象物からの反射光を前記受光部5に向けて反射する受光ミラー10と、投光ミラー9及び受光ミラー10を投光部3と受光部5を結ぶ軸心周りに回転させる回転機構としてのモータ11を備えて構成されている。 That is, the scanning unit 4 includes a light projecting mirror 9 that reflects the pulsed measurement light toward the measurement target space, a light receiving mirror 10 that reflects the reflected light from the measurement target toward the light receiving unit 5, and a light projection. A motor 11 is provided as a rotation mechanism that rotates the optical mirror 9 and the light receiving mirror 10 around the axis connecting the light projecting unit 3 and the light receiving unit 5.
なお、本実施形態では、投光ミラー9及び受光ミラー10は、回転体8の回転軸に対してそれぞれ45度で傾斜しており、投光出射光路L2及び受光出射光路L3とが、投光入射光路L3の光軸(受光入射光路L4の光軸)と直交する光軸をそれぞれ有し、互いに平行となるように設定されている。これにより、投光出射光路L1により物体に照射されて反射する反射光を、受光入射光路L3から取り込むことが可能となる。また、回転体8の周壁部8aの一部に開口部8a1が形成されており、この開口部8a1に受光レンズ14が取り付けられている。これにより、物体からの反射光が受光部5で集束されるようになっている。さらに、回転体8の走査角度を検出する走査角度検出部15が、回転体8の外周面に固定された光学的スリットを有するスリット板15aと、スリット板15aの回転経路上に配置されたフォトインタラプタ15bとから構成されている。 In the present embodiment, the light projecting mirror 9 and the light receiving mirror 10 are inclined at 45 degrees with respect to the rotation axis of the rotating body 8, respectively, and the light projecting and emitting light path L2 and the light receiving and emitting light path L3 are Each has an optical axis perpendicular to the optical axis of the light incident optical path L3 (the optical axis of the light receiving incident optical path L4), and is set to be parallel to each other. As a result, it is possible to take in reflected light that is irradiated and reflected on the object through the light projecting and exiting optical path L1 from the light receiving incident optical path L3. An opening 8a1 is formed in a part of the peripheral wall 8a of the rotating body 8, and the light receiving lens 14 is attached to the opening 8a1. Thereby, the reflected light from the object is focused by the light receiving unit 5. Further, the scanning angle detector 15 for detecting the scanning angle of the rotator 8 includes a slit plate 15a having an optical slit fixed to the outer peripheral surface of the rotator 8, and a photo arranged on the rotation path of the slit plate 15a. It is comprised from the interrupter 15b.
受光部5は、例えばアバランシェフォトダイオードなどの受光素子と、光電変換された信号を増幅する増幅回路を備えて構成され、回転体8の内部に収容された状態で投光部3と対向するように受光入射光路L4上に配置されている。詳述すると、受光部5は、回転体8を支承する中空軸13の上端面に配置されており、モータ11による回転体8の回転動作とは無関係に、常に静止状態を維持するようになっている。また、受光部5からの出力信号は、図示していないが、中空軸13の内部空間に挿通された信号線により後述の信号処理回路に接続されている。 The light receiving unit 5 includes a light receiving element such as an avalanche photodiode and an amplifier circuit that amplifies the photoelectrically converted signal, and faces the light projecting unit 3 while being accommodated inside the rotating body 8. Are arranged on the light receiving incident optical path L4. More specifically, the light receiving unit 5 is disposed on the upper end surface of the hollow shaft 13 that supports the rotating body 8, and always maintains a stationary state regardless of the rotating operation of the rotating body 8 by the motor 11. ing. Although not shown, the output signal from the light receiving unit 5 is connected to a signal processing circuit described later by a signal line inserted into the internal space of the hollow shaft 13.
光ファイバ6は、一端部から投光出射光路L2上の測定光の一部を受光し、その受光した光を他端部から受光ミラー10に向けて出射するように、両端部が回転体8の天板部8bの上下面に取り付けられており、投光部3から出力された測定光の一部が、投光ミラー9で反射された後、光ファイバ6により受光ミラー10へと導かれると共に反射され、受光部5で受光される。つまり、測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路が形成され、光ファイバ6が、回転機構11により回転し、投光ミラー9で反射した測定光の一部を受光ミラー10に導く導光部材となる。 The optical fiber 6 receives a part of the measurement light on the light projecting and exiting optical path L2 from one end, and both ends are rotating bodies so that the received light is emitted from the other end toward the light receiving mirror 10. 8 is attached to the upper and lower surfaces of the top plate portion 8b, and part of the measurement light output from the light projecting portion 3 is reflected by the light projecting mirror 9 and then guided to the light receiving mirror 10 by the optical fiber 6. It is reflected and reflected and received by the light receiving unit 5. That is, a reference optical path that leads a part of the measurement light to the light receiving unit with a constant optical path length as a reference light is formed, and the optical fiber 6 is rotated by the rotation mechanism 11 and is reflected by the projection mirror 9. The light guide member guides the part to the light receiving mirror 10.
回転体8を回転させると、投光部3から出力された測定光は、回転体8の回転軸を中心とする周囲360度に亘って走査され、両端部が回転体8に取り付けられた光ファイバ6も回転体8と一体に回転する。従って、投光部3から出力されるパルス状の測定光は、回転機構11により周囲360度に連続して走査され、同時に測定光の一部が基準光路を経由して受光部5に導かれる一方、測定対象空間に向けて走査される測定光の一部が測定対象物から反射して受光部5に導かれる。 When the rotator 8 is rotated, the measurement light output from the light projecting unit 3 is scanned over 360 degrees around the rotation axis of the rotator 8, and both ends are attached to the rotator 8. The fiber 6 also rotates integrally with the rotating body 8. Accordingly, the pulsed measurement light output from the light projecting unit 3 is continuously scanned at 360 degrees around by the rotating mechanism 11, and at the same time, part of the measurement light is guided to the light receiving unit 5 via the reference optical path. On the other hand, part of the measurement light scanned toward the measurement object space is reflected from the measurement object and guided to the light receiving unit 5.
図2に示すように、通常、受光部5からは、先ず基準光S3に対応した基準信号S5aが出力され、その後、測定対象物からの反射光S4に対応した反射信号S5bが出力される。つまり、受光部5の出力信号S5は、基準信号S5aと反射信号S5bで構成される。この基準信号S5aと反射信号S5bとの時間差t5に基づいて物体までの距離を演算すれば、投光部3や受光部5での光電変換の遅延時間t2、t4の変動など、装置内部の不安定要素の変動の影響を的確に低減することができ、周囲360度の全方位に亘って物体までの距離を高精度に演算することができる。 As shown in FIG. 2, the light receiving unit 5 normally outputs a reference signal S5a corresponding to the reference light S3, and then outputs a reflected signal S5b corresponding to the reflected light S4 from the measurement object. That is, the output signal S5 of the light receiving unit 5 is composed of the reference signal S5a and the reflection signal S5b. If the distance to the object is calculated on the basis of the time difference t5 between the reference signal S5a and the reflected signal S5b, there is a problem in the apparatus such as fluctuations in the photoelectric conversion delay times t2 and t4 in the light projecting unit 3 and the light receiving unit 5. The influence of fluctuations in the stability factor can be accurately reduced, and the distance to the object can be calculated with high accuracy over all 360 degrees around.
以下、詳述する。測定光のうち基準光路を経由する基準光S3と物体からの反射光S4とが同一の受光部5で受光されるため、受光部5で基準光S3が受光されて基準信号S5aが出力されるまでの遅延時間t3と、受光部5で反射光S4が受光されて反射信号S5bが出力されるまでの遅延時間t4とはともに一致することになる。従って、基準信号S5aと反射信号S5bとの時間差t5の測定は、受光部5で基準光S3を受光してから反射光S4を受光するまでの時間差t6の測定と等価となり、基準信号S5aと反射信号S5bに基づいて物体までの距離を演算すれば、受光部5での応答時間t4の影響を受けることがなくなる。 Details will be described below. Of the measurement light, the reference light S3 passing through the reference optical path and the reflected light S4 from the object are received by the same light receiving unit 5, so the light receiving unit 5 receives the reference light S3 and outputs a reference signal S5a. And the delay time t4 until the reflected light S4 is received by the light receiving unit 5 and the reflected signal S5b is output coincide with each other. Therefore, the measurement of the time difference t5 between the reference signal S5a and the reflected signal S5b is equivalent to the measurement of the time difference t6 from the reception of the reference light S3 by the light receiving unit 5 to the reception of the reflected light S4. If the distance to the object is calculated based on the signal S5b, it is not affected by the response time t4 in the light receiving unit 5.
さらに、基準信号S5aを基準として距離を演算するため、投光部3に発光駆動信号(以下、「トリガ信号」と記す場合もある。)S1が入力されてから実際にパルス光が出射されるまでの遅延時間t2の影響を受けることもなくなる。投光部3から測定光S2が出力されてから受光部5で基準光S3が受光されるまでの時間差t7は、基準光路の光路長が短いこと、及び光の速度が高速であることから測定精度には実質上の影響がない。また、この時間差t7を距離に換算すると、既知である基準光路の光路長に対応するものであるから、距離演算時に補正することも可能である。従って、基準信号S5aと反射信号S5bとの時間差t6は、投光部3から実際に測定光S2が出力されたタイミングから反射光S4を受光部5で受光するタイミングまでの時間差t1を直接測定することと略相違がなく、この時間差t5に基づいて物体までの距離を演算すれば、上述のように装置内部の回路の応答性等の不安定要素の影響が効果的に低減され、高精度な距離測定を実現することが可能となる。 Further, in order to calculate the distance based on the reference signal S5a, the pulsed light is actually emitted after the light emission drive signal (hereinafter sometimes referred to as “trigger signal”) S1 is input to the light projecting unit 3. It is no longer affected by the delay time t2. The time difference t7 from when the measurement light S2 is output from the light projecting unit 3 to when the reference light S3 is received by the light receiving unit 5 is measured because the optical path length of the reference optical path is short and the speed of light is high. There is virtually no effect on accuracy. Further, when this time difference t7 is converted into a distance, it corresponds to the known optical path length of the reference optical path, and therefore it can be corrected when calculating the distance. Therefore, the time difference t6 between the reference signal S5a and the reflected signal S5b directly measures the time difference t1 from the timing when the measurement light S2 is actually output from the light projecting unit 3 to the timing when the reflected light S4 is received by the light receiving unit 5. If the distance to the object is calculated based on this time difference t5, the influence of unstable elements such as the responsiveness of the circuit inside the apparatus is effectively reduced as described above, and high accuracy is achieved. Distance measurement can be realized.
なお、上述した第1の実施形態では、投光ミラー9と受光ミラー10とを別個の部材で形成したものを説明したが、双方のミラー9、10を単一の部材の表面に一体に形成したものであってもよい。 In the above-described first embodiment, the light projecting mirror 9 and the light receiving mirror 10 are formed of separate members. However, both the mirrors 9 and 10 are integrally formed on the surface of a single member. It may be what you did.
図3は、本発明の第2の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。この実施形態は、基準光路の構成のみが上記の第1の実施形態と相違するものである。以下では、相違点となる基準光路の構成を中心に説明し、共通の構成要素については同符号を付して詳しい説明を省略する。 FIG. 3 is a schematic longitudinal sectional view showing the overall configuration of the scanning distance measuring apparatus according to the second embodiment of the present invention. This embodiment is different from the first embodiment only in the configuration of the reference optical path. Below, it demonstrates centering around the structure of the reference | standard optical path used as a difference, and attaches | subjects the same code | symbol about a common component, and abbreviate | omits detailed description.
同図に示すように、この走査式測距装置21における基準光路は、回転機構11による回転軸心と同軸心に配置され、投光ミラー9で反射した測定光の一部を受光ミラー10に導く円環状の反射部材22を備えて構成されている。つまり、投光出射光路L2上に配置された円環状の反射部材22により、投光出射光路L2内の測定光の一部が受光ミラー10に向けて反射(散乱)されるので、回転体8の回転動作に伴って、走査領域の全域に亘って同様にして基準光路が形成されることとなる。なお、本実施形態では、反射部材22は、ハウジング2の透光窓2a1の周方向に沿って配置されている。この場合、円筒状のハウジング2の中心軸と、回転体8の回転軸とを一致させることが肝要となる。また、反射部材22としては、例えば透光窓2a1に蒸着等の手法により反射膜を成膜したものや、或いは反射フィルムを透光窓2a1に接着したもの等を利用することができる。 As shown in the figure, the reference optical path in the scanning distance measuring device 21 is arranged coaxially with the rotation axis of the rotation mechanism 11, and a part of the measurement light reflected by the light projection mirror 9 is applied to the light receiving mirror 10. An annular reflecting member 22 for guiding is provided. In other words, a part of the measurement light in the light projecting and exiting optical path L2 is reflected (scattered) toward the light receiving mirror 10 by the annular reflecting member 22 disposed on the light projecting and exiting optical path L2. As the body 8 rotates, the reference optical path is similarly formed over the entire scanning region. In the present embodiment, the reflecting member 22 is disposed along the circumferential direction of the light transmitting window 2 a 1 of the housing 2. In this case, it is important to make the central axis of the cylindrical housing 2 coincide with the rotation axis of the rotating body 8. In addition, as the reflecting member 22, for example, a member in which a reflective film is formed on the light transmitting window 2a1 by a method such as vapor deposition or a member in which a reflecting film is bonded to the light transmitting window 2a1 can be used.
図4は、本発明の第3の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。この実施形態は、基準光路の構成のみが上記の第1及び第2の実施形態と相違するものである。以下では、相違点となる基準光路を中心に説明し、共通の構成要素については同一符号を付して詳しい説明を省略する。 FIG. 4 is a schematic longitudinal sectional view showing the overall configuration of a scanning distance measuring apparatus according to the third embodiment of the present invention. This embodiment is different from the first and second embodiments only in the configuration of the reference optical path. In the following description, the reference optical path as a difference will be mainly described, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.
同図に示すように、この走査式測距装置31における前記基準光路は、前記回転機構11による回転軸心に沿って投光部9から受光部10に測定光の一部を導くように構成されている。具体的には、投光出射光路L1の光軸(回転体8の回転軸)上に、投光ミラー9、回転体8の天板部8b、及び受光ミラー10に連通する貫通孔32を形成し、この貫通孔32により、投光出射光路L1上の光の一部を受光部5に直接受光させるように基準光路が形成されている。この基準光路は、回転体8の回転軸と一致していることから、回転体8の走査角度によらず常に基準光路を介して受光部10に基準光が導かれる。なお、貫通孔に代えて、投光ミラー9及び受光ミラー10に形成される鏡面のうち前記軸心と交差する部位を非鏡面である透過面に、つまり測定光の一部を透過させるように基準光路を構成することも可能である。 As shown in the figure, the reference optical path in the scanning distance measuring device 31 is configured to guide part of the measurement light from the light projecting unit 9 to the light receiving unit 10 along the rotation axis of the rotation mechanism 11. Has been. Specifically, a through hole 32 communicating with the light projecting mirror 9, the top plate portion 8 b of the rotating body 8, and the light receiving mirror 10 is provided on the optical axis of the light projecting and emitting optical path L <b> 1 (the rotating shaft of the rotating body 8). The reference optical path is formed by the through hole 32 so that a part of the light on the light projecting and emitting optical path L1 is directly received by the light receiving unit 5. Since this reference optical path coincides with the rotation axis of the rotator 8, the reference light is always guided to the light receiving unit 10 via the reference optical path regardless of the scanning angle of the rotator 8. In place of the through-hole, a portion of the mirror surface formed on the light projecting mirror 9 and the light receiving mirror 10 that intersects the axis is transmitted through a non-specular transmission surface, that is, a part of the measurement light is transmitted. It is also possible to configure a reference optical path.
図5は、本発明の第4の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。この実施形態は、投光部3からの測定光を走査部43に向けて反射するミラー42をさらに備え、走査部43はミラー42で反射された測定光を測定対象空間に向けて反射するとともに、測定対象物からの反射光を受光部5に向けて反射する投受光ミラー47と、投受光ミラー47を所定の軸心周りに回転させる回転機構48を備えて構成され、基準光路は、測定光の一部をミラー42を介さずに受光部5に導く導光部材を備えて構成されている。以下では、上述の第1から第3の実施形態との相違点を中心に説明し、共通の構成要素については同一符号を付して詳しい説明を省略する。 FIG. 5 is a schematic longitudinal sectional view showing the overall configuration of a scanning distance measuring apparatus according to the fourth embodiment of the present invention. This embodiment further includes a mirror 42 that reflects the measurement light from the light projecting unit 3 toward the scanning unit 43, and the scanning unit 43 reflects the measurement light reflected by the mirror 42 toward the measurement target space. The light projecting / receiving mirror 47 that reflects the reflected light from the measurement object toward the light receiving unit 5 and the rotating mechanism 48 that rotates the light projecting / receiving mirror 47 around a predetermined axis are configured, and the reference optical path is measured. A light guide member that guides part of the light to the light receiving unit 5 without using the mirror 42 is provided. Below, it demonstrates centering around difference with the above-mentioned 1st to 3rd embodiment, attaches | subjects the same code | symbol about a common component, and abbreviate | omits detailed description.
同図に示すように、この走査式測距装置41は、ハウジング2を備えると共に、このハウジング2の内部に、投光部3と、受光部5と、ミラー42と、走査部43と、導光部材としての光ファイバ44とを主たる構成要素として備えている。 As shown in the figure, the scanning distance measuring device 41 includes a housing 2, and a light projecting unit 3, a light receiving unit 5, a mirror 42, a scanning unit 43, and a light guide are provided inside the housing 2. An optical fiber 44 as an optical member is provided as a main component.
投光部3は、図中の左右方向に測定光を出射するように配置されている。そして、投光部3から左右方向に出射された測定光が通る第1の投光出射光路L5上には、投光部3から出射されたパルス光のビーム径を一定にするために光学レンズ45aと、この第1の投光出射光路L5の光軸A5に対して傾斜したミラー42が配置されており、第1の投光出射光路L5を通る測定光を下向きに反射して第2の投光出射光路L6に導くようになっている。 The light projecting unit 3 is arranged to emit measurement light in the left-right direction in the drawing. In order to make the beam diameter of the pulsed light emitted from the light projecting unit 3 constant on the first light projecting and emitting light path L5 through which the measurement light emitted from the light projecting unit 3 in the left-right direction passes. A lens 45a and a mirror 42 inclined with respect to the optical axis A5 of the first light projecting and exiting optical path L5 are disposed, and the measurement light passing through the first light projecting and exiting optical path L5 is reflected downward. The light is guided to the second light projecting and emitting light path L6.
第2の投光出射光路L6の下方位置に、第2の投光出射光路L6の光軸A6を回転軸として回転駆動される回転体46が配置されている。回転体46の上端部には、回転体46の回転軸に対して例えば45度で傾斜した状態で投受光ミラー47が取り付けられている。一方、回転体46の下端部には、回転体46を回転駆動する回転機構としてのモータ48が連結されている。このようにして、回転体46と、投受光ミラー47と、モータ48とから走査部43が構成されている。そして、第2の投光出射光路L6によって投受光ミラー47に入射した光は、投受光ミラー47で反射され投光出射光路L7に導かれる。 A rotating body 46 that is driven to rotate about the optical axis A6 of the second light projecting and emitting light path L6 is disposed below the second light projecting and emitting light path L6. A light projecting / receiving mirror 47 is attached to the upper end portion of the rotating body 46 so as to be inclined at, for example, 45 degrees with respect to the rotation axis of the rotating body 46. On the other hand, a motor 48 as a rotation mechanism for rotating the rotation body 46 is connected to the lower end portion of the rotation body 46. In this manner, the scanning unit 43 is configured by the rotating body 46, the light projecting / receiving mirror 47, and the motor 48. The light incident on the light projecting / receiving mirror 47 through the second light projecting / emitting light path L6 is reflected by the light projecting / receiving mirror 47 and guided to the light projecting / emitting light path L7.
一方、ハウジング2の外方の測定対象空間に存在する物体からの反射光は、投光出射光路L7と逆向きの光路となる受光入射光路L8により再度投受光ミラー47に入射した後、第2の投光入射光路L6と逆向きの光路となる第1の受光出射光路L9によりミラー42の周部を通過して受光部5へと入射する。第1の受光出射光路L9の光軸は第2の投光出射光路L6の光軸A6と一致するように構成され、その光路L9上には反射光を受光部5に合焦させる光学レンズ45bが配置されている。 On the other hand, the reflected light from the object existing in the measurement target space outside the housing 2 is incident on the light projecting / receiving mirror 47 again by the light receiving / incident light path L8 which is the light path opposite to the light projecting / emitting light path L7, The light is incident on the light receiving unit 5 through the periphery of the mirror 42 by the first light receiving and emitting light path L9 which is an optical path opposite to the light projecting incident light path L6. The optical axis of the first light receiving and emitting optical path L9 is configured to coincide with the optical axis A6 of the second light projecting and emitting optical path L6, and the optical for focusing the reflected light on the light receiving unit 5 on the optical path L9. A lens 45b is disposed.
この走査式測距装置41における基準光路は、投光部3から出力された測定光が、ミラー42に入射する前に、その一部を光ファイバ44で受光部5に導くことで形成される。この場合、投光部3と受光部5は、回転体46の回転動作とは無関係であることから、回転体46を回転させても、投光部3と受光部5に対する光ファイバ44の相対的な位置関係は一定に保たれる。従って、回転体の角度位置によらず、走査領域の全域に亘って、基準光路が形成されることとなる。 The reference optical path in the scanning distance measuring device 41 is formed by guiding a part of the measurement light output from the light projecting unit 3 to the light receiving unit 5 through the optical fiber 44 before entering the mirror 42. . In this case, since the light projecting unit 3 and the light receiving unit 5 are irrelevant to the rotation operation of the rotating body 46, the relative position of the optical fiber 44 with respect to the light projecting unit 3 and the light receiving unit 5 even if the rotating body 46 is rotated. The positional relationship is kept constant. Therefore, the reference optical path is formed over the entire scanning region regardless of the angular position of the rotating body.
図6は、本発明の第5の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。この実施形態は、上記の第4実施形態と基準光路の構成のみが相違するもので、基準光路は、回転機構48による回転軸心と同軸心に配置され、投受光ミラー47で反射された測定光の一部を投受光ミラー47に導く円環状の反射部材52を備えて構成されている。以下では、相違点となる基準光路の構成について説明し、共通の構成要素については同一符号を付して詳しい説明を省略する。 FIG. 6 is a schematic longitudinal sectional view showing the overall configuration of a scanning distance measuring apparatus according to the fifth embodiment of the present invention. This embodiment differs from the fourth embodiment only in the configuration of the reference optical path. The reference optical path is arranged coaxially with the rotation axis of the rotation mechanism 48 and is reflected by the light projecting / receiving mirror 47. An annular reflecting member 52 that guides part of the light to the light projecting / receiving mirror 47 is provided. In the following, the configuration of the reference optical path that is the difference will be described, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.
この走査式測距装置51における基準光路は、投光出射光路L7上に配置された反射部材52で、投光出射光路L7内の光の一部を投受光ミラー47に向けて再度反射(散乱)させることで形成されている。さらに、この反射部材52は、回転体46の回転軸を中心とする円環状を呈していることから、回転体46の回転動作に伴って、走査領域の全域に亘って同様にして基準光路が形成されることとなる。なお、本実施形態では、反射部材52は、ハウジング2の透光窓2a1の周方向に沿って配置されている。この場合、円筒状のハウジング2の上下方向中心線と、回転体46の回転軸とを一致させることが肝要となる。また、反射部材52としては、例えば透光窓2a1に蒸着等の手法により反射膜を成膜したものや、或いは所定の反射体を接着したもの等を利用することができる。 The reference optical path in the scanning distance measuring device 51 is a reflecting member 52 disposed on the light projecting / emission optical path L7, and part of the light in the light projecting / emission optical path L7 is reflected again toward the light projecting / receiving mirror 47. It is formed by (scattering). Further, since the reflecting member 52 has an annular shape centering on the rotation axis of the rotator 46, the reference optical path is similarly extended over the entire scanning region as the rotator 46 rotates. Will be formed. In the present embodiment, the reflecting member 52 is disposed along the circumferential direction of the light transmitting window 2 a 1 of the housing 2. In this case, it is important to match the vertical center line of the cylindrical housing 2 with the rotation axis of the rotating body 46. Further, as the reflecting member 52, for example, a member in which a reflecting film is formed on the transparent window 2a1 by a method such as vapor deposition, or a member in which a predetermined reflector is adhered can be used.
図7は、本発明の第6の実施形態に係る走査式測距装置の全体構成を示す概略縦断面図である。この実施形態は、上記の第4及び第5の実施形態と基準光路の構成のみが相違するもので、基準光路は、回転機構48により回転し、前記投受光ミラー47で反射された測定光の一部を投受光ミラー47に向けて反射する反射部材62を備えて構成されている。以下では、相違点となる基準光路の構成について説明し、共通の構成要素については同一符号を付して詳しい説明を省略する。 FIG. 7 is a schematic longitudinal sectional view showing the overall configuration of a scanning distance measuring apparatus according to the sixth embodiment of the present invention. This embodiment is different from the above fourth and fifth embodiments only in the configuration of the reference optical path. The reference optical path is rotated by the rotation mechanism 48 and the measurement light reflected by the light projecting / receiving mirror 47 is reflected. A reflection member 62 that partially reflects toward the light projecting / receiving mirror 47 is provided. In the following, the configuration of the reference optical path that is the difference will be described, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.
同図に示すように、この走査式測距装置61における基準光路は、回転体46と一体に回転する反射部材62を投光出射光路L7と受光入射光路L8の共通部分に配置し、投光部3から出射され投受光ミラー47で反射されたパルス光を反射部材62で再度投受光ミラー10に向けて反射することで形成される。さらに、回転体46の回転に伴って、投受光ミラー47と反射部材62とが一体に回転するので、走査領域の全域に亘って同様にして基準光路が形成されることとなる。 As shown in the figure, the reference optical path in the scanning distance measuring device 61 is configured such that a reflecting member 62 that rotates integrally with the rotating body 46 is disposed at a common part of the light projecting and emitting light path L7 and the light receiving and incident light path L8. The pulse light emitted from the light unit 3 and reflected by the light projecting / receiving mirror 47 is reflected again by the reflecting member 62 toward the light projecting / receiving mirror 10. Further, since the light projecting / receiving mirror 47 and the reflecting member 62 rotate integrally with the rotation of the rotating body 46, the reference optical path is formed in the same manner over the entire scanning region.
以下に、上述した第1〜第6の実施形態に係る走査式測距装置において、測定光の出力タイミングに同期して受光部により検出される基準光と反射光の検出時間差に基づいて測定対象物までの距離を算出する演算部を含む信号処理回路について説明する。 In the scanning rangefinder according to the first to sixth embodiments described above, the measurement target is based on the detection time difference between the reference light and the reflected light detected by the light receiving unit in synchronization with the output timing of the measurement light. A signal processing circuit including a calculation unit that calculates the distance to an object will be described.
図8に示すように、信号処理回路70は、受光部5で光電変換されたアナログ信号S5をデジタル信号に変換するAD変換器73と、AD変換器73で変換されたデジタル信号に基づいて基準信号S5a(図2参照)及び反射信号S5b(図2参照)の時間差を算出するFPGAで構成される信号処理部72と、システム全体を制御するとともに信号処理部72で算出された時間差に基づいて距離情報を算出するCPUを備えたシステム制御部71等を備えて構成される。 As shown in FIG. 8, the signal processing circuit 70 includes an AD converter 73 that converts the analog signal S5 photoelectrically converted by the light receiving unit 5 into a digital signal, and a reference based on the digital signal converted by the AD converter 73. Based on the signal processing unit 72 composed of an FPGA that calculates the time difference between the signal S5a (see FIG. 2) and the reflected signal S5b (see FIG. 2), and the time difference calculated by the signal processing unit 72 while controlling the entire system. A system control unit 71 including a CPU for calculating distance information is provided.
システムに電源が投入されると、システム制御部71からモータ制御回路74にモータ駆動信号が出力され、モータ制御回路74によりモータ11が所定速度で駆動される。モータの回転駆動に伴って走査角度検出部15から出力されるパルス信号がシステム制御部71に入力され、当該パルス信号に基づいてシステム制御部71では走査部4による測定光の出力方向が把握される。なお、走査角度検出部15を構成するスリット板15aのスリット間隔が予め設定された回転体の基準位置で他と異なるように形成されているため、パルス信号の波形に基づいて基準位置が検出され、基準位置からのパルス数をカウントすることにより基準位置からの回転角度が算出される。 When the system is powered on, a motor drive signal is output from the system control unit 71 to the motor control circuit 74, and the motor 11 is driven at a predetermined speed by the motor control circuit 74. A pulse signal output from the scanning angle detection unit 15 as the motor is driven to rotate is input to the system control unit 71, and the system control unit 71 grasps the output direction of the measurement light from the scanning unit 4 based on the pulse signal. The In addition, since the slit interval of the slit plate 15a constituting the scanning angle detection unit 15 is formed so as to be different from the other reference position of the rotary body set in advance, the reference position is detected based on the waveform of the pulse signal. The rotation angle from the reference position is calculated by counting the number of pulses from the reference position.
図10に示すように、走査角度検出部15から出力されるパルス信号に基づいて計測タイミングを算出したシステム制御部71から、信号処理部72のパルス信号生成部723(図9参照)に計測タイミング信号が入力されると、パルス信号生成部723から当該計測タイミング信号を基準とする所定タイミングでAD変換器73に変換開始信号が出力されるとともに、変換開始信号から僅かに遅れて投光部3に所定のデューティ比の発光駆動信号S1が出力される。投光部3に備えた発光素子が当該発光駆動信号S1に同期して駆動され、パルス状の測定光S2が出力される。つまり、測定光S2の発光強度は当該発光駆動信号のデューティ比及び発光素子の駆動電流により制御され、所定周期で出力される計測タイミング信号と同周期で発光素子が間歇駆動される。 As shown in FIG. 10, the measurement timing is sent from the system control unit 71 that calculates the measurement timing based on the pulse signal output from the scanning angle detection unit 15 to the pulse signal generation unit 723 (see FIG. 9) of the signal processing unit 72. When a signal is input, a conversion start signal is output from the pulse signal generation unit 723 to the AD converter 73 at a predetermined timing based on the measurement timing signal, and the light projecting unit 3 is slightly delayed from the conversion start signal. A light emission drive signal S1 having a predetermined duty ratio is output. The light emitting element provided in the light projecting unit 3 is driven in synchronization with the light emission drive signal S1, and the pulsed measurement light S2 is output. That is, the emission intensity of the measurement light S2 is controlled by the duty ratio of the emission drive signal and the drive current of the light emitting element, and the light emitting element is intermittently driven at the same cycle as the measurement timing signal output at a predetermined cycle.
発光素子が駆動されると、測定光S2の一部が基準光S3として上述の基準光路を介して受光部5で検出されて基準信号S5aが生成され、測定対象空間に出力された測定光S2の測定対象物からの反射光S4が受光部5で検出されて反射信号S5bが生成される。つまり、基準信号S5aと反射信号S5bが受光部5で光電変換されたアナログの出力信号S5となる。 When the light emitting element is driven, a part of the measurement light S2 is detected as the reference light S3 by the light receiving unit 5 through the above-described reference optical path, and the reference signal S5a is generated, and the measurement light S2 output to the measurement target space. The reflected light S4 from the measurement object is detected by the light receiving unit 5, and a reflected signal S5b is generated. That is, the reference signal S5a and the reflected signal S5b become an analog output signal S5 obtained by photoelectric conversion by the light receiving unit 5.
アナログの出力信号S5はAD変換器73により所定のサンプリング周波数fsでサンプリングされてデジタル信号に変換されて信号処理部72に出力される。信号処理部72では、デジタル変換された基準信号S5aと反射信号S5bの時間差が算出され、システム制御部71では信号処理部72により算出された時間差と走査角度検出部15からの信号入力に基づいて測定対象物までの距離及び方向が算出される。 The analog output signal S5 is sampled by the AD converter 73 at a predetermined sampling frequency fs, converted into a digital signal, and output to the signal processing unit 72. The signal processing unit 72 calculates the time difference between the digitally converted reference signal S5a and the reflected signal S5b. The system control unit 71 calculates the time difference calculated by the signal processing unit 72 and the signal input from the scanning angle detection unit 15. The distance and direction to the measurement object are calculated.
以下に、信号処理部72の構成及びその動作について詳述する。図9に示すように、信号処理部72は、第一メモリ721と、ローパスフィルタ722と、基準信号S5a及び反射信号S5bの夫々を微分する微分処理部724と、閾値設定部725と、反射光光量検出部726と、基準光光量検出部727と、微分された基準信号S5a及び反射信号S5bから時間差を算出する時間差検出部728と、各種の演算結果を記憶する第二メモリ729と、トリガ信号を生成するパルス信号生成部723等を備えている。ここでメモリはRAM等の半導体メモリが用いられる。 Hereinafter, the configuration and operation of the signal processing unit 72 will be described in detail. As shown in FIG. 9, the signal processing unit 72 includes a first memory 721, a low-pass filter 722, a differentiation processing unit 724 that differentiates each of the reference signal S5a and the reflection signal S5b, a threshold setting unit 725, and reflected light. A light amount detector 726, a reference light amount detector 727, a time difference detector 728 that calculates a time difference from the differentiated reference signal S5a and reflected signal S5b, a second memory 729 that stores various calculation results, and a trigger signal A pulse signal generation unit 723 and the like. Here, a semiconductor memory such as a RAM is used as the memory.
第一メモリ721にはAD変換器73により変換されたデジタル信号が時系列的に一時記憶される。第一メモリ721から読み出されたデジタル信号はローパスフィルタ722により高周波ノイズ成分が除去されて微分処理部724等に供給される。 The first memory 721 temporarily stores the digital signal converted by the AD converter 73 in time series. A high frequency noise component is removed from the digital signal read from the first memory 721 by the low-pass filter 722, and the digital signal is supplied to the differentiation processing unit 724 and the like.
微分処理部724は、ローパスフィルタ722を通過した基準信号S5aと反射信号S5bを含む出力信号S5を微分処理して時間差検出部728に出力する。詳述すると、反射信号S5bに対しては、図11(a)に示すように、K番目(Kはサンプリング順序を示す自然数である)のサンプリング値とK−1番目のサンプリング値の差分を各Kについて求め、その値を同図(b)に示すような微分信号として算出する。なお、本実施形態では、差分値が負となる場合には零に丸め込み、正領域のみ抽出するように構成されている。また、基準信号S5aに対してはそのまま微分処理するのではなく、後述の累積加算波形生成部で求められる累積加算波形データに対して上述と同様の微分処理が行なわれるように構成されている。 The differential processing unit 724 performs differential processing on the output signal S5 including the reference signal S5a and the reflected signal S5b that has passed through the low-pass filter 722, and outputs the result to the time difference detection unit 728. Specifically, for the reflected signal S5b, as shown in FIG. 11 (a), the difference between the Kth (K is a natural number indicating the sampling order) sampling value and the (K-1) th sampling value is calculated for each difference. K is obtained and its value is calculated as a differential signal as shown in FIG. In this embodiment, when the difference value is negative, it is rounded to zero and only the positive region is extracted. The reference signal S5a is not subjected to differentiation processing as it is, but is configured such that differentiation processing similar to that described above is performed on cumulative addition waveform data obtained by a cumulative addition waveform generation unit described later.
閾値設定部725は、ローパスフィルタ722を通過したデジタルの出力信号S5のうち、基準信号S5a生成前の信号の最大レベルから最小レベルを減算して、基準信号S5aと反射信号S5bを検出するための第一測定閾値L1を算出するとともに、基準信号S5a生成前の信号の平均レベルをオフセット値に対応した第二測定閾値L2として算出する。 The threshold setting unit 725 detects the reference signal S5a and the reflected signal S5b by subtracting the minimum level from the maximum level of the signal before the generation of the reference signal S5a in the digital output signal S5 that has passed through the low-pass filter 722. The first measurement threshold L1 is calculated, and the average level of the signal before generating the reference signal S5a is calculated as the second measurement threshold L2 corresponding to the offset value.
つまり、変換開始信号が出力された後、発光駆動信号S1が出力されるまでの間は、基準光や反射光が検出されることなく、微小な外乱光によるノイズ信号がオフセットレベルに重畳した信号がサンプリングされるので、その間にオフセットレベルやノイズレベルが算出されるのである。算出された第一測定閾値L1は時間差検出部728に出力され、第一及び第二測定閾値L1,L2は反射光光量検出部726及び基準光光量検出部727に出力される。 That is, after the conversion start signal is output and before the light emission drive signal S1 is output, the signal in which the noise signal due to minute disturbance light is superimposed on the offset level without detecting the reference light or the reflected light. Are sampled, the offset level and noise level are calculated during that time. The calculated first measurement threshold L1 is output to the time difference detection unit 728, and the first and second measurement thresholds L1 and L2 are output to the reflected light amount detection unit 726 and the reference light amount detection unit 727.
時間差検出部728は、微分処理部724から入力される微分信号から、第一測定閾値L1より大となる領域の信号成分を抽出し、その正側領域(図10に示す微分波形の実線部)の重心位置を立上りタイミングとして算出し、測定光の出力タイミングから基準信号S5aの立上りタイミングまでの時間差、つまり基準光遅延時間Δt1と、測定光の出力タイミングから反射信号S5bの立上りタイミングまでの時間差、つまり反射光遅延時間Δt2を求めて、その結果を第二メモリ729に格納する。 The time difference detection unit 728 extracts a signal component in a region larger than the first measurement threshold L1 from the differential signal input from the differentiation processing unit 724, and the positive side region (solid line portion of the differential waveform shown in FIG. 10). Is calculated as the rise timing, and the time difference from the output timing of the measurement light to the rise timing of the reference signal S5a, that is, the reference light delay time Δt1, and the time difference from the output timing of the measurement light to the rise timing of the reflected signal S5b, That is, the reflected light delay time Δt 2 is obtained, and the result is stored in the second memory 729.
具体的に反射信号S5bを例に説明すると、図11に示すように、微分信号のうち第一測定閾値L1を二回連続して超えるサンプリングポイントを検出し、二回目に第一測定閾値L1を超えたポイントの微分信号値Dnを中心として、例えば前後に連続する10点のサンプリングポイント(n−10〜n+10)を重心演算範囲R1として、〔数1〕に示す数式に基づいて重心位置Pを算出する。つまり、重心位置Pはサンプリングポイント(n−10)からの時間情報として算出される。このような処理を基準信号S5aの累積加算波形データに対しても行なうことにより、それぞれの重心位置Pが求められる。 Specifically, the reflected signal S5b will be described as an example. As shown in FIG. 11, a sampling point that exceeds the first measurement threshold L1 twice in the differential signal is detected, and the first measurement threshold L1 is set for the second time. For example, 10 sampling points (n−10 to n + 10) consecutive in the front and rear are centered on the differential signal value Dn at the point exceeding the center of gravity calculation range R1, and the center of gravity position P is calculated based on the formula shown in [Equation 1]. calculate. That is, the gravity center position P is calculated as time information from the sampling point (n-10). By performing such processing also on the cumulative added waveform data of the reference signal S5a, the respective gravity center positions P are obtained.
一般に、反射光の光量は測定対象物の反射特性により変動するため、反射信号S5bの立上りタイミングを所定の閾値を超えたタイミングとして求める場合には、反射光が同じタイミングで受光部5に入射しても、その光量によって立上り特性が異なり僅かな誤差が発生するが、反射信号S5bを微分してその正側領域の重心位置として求める場合には、光量が異なる場合であってもほぼ等しい値として求まるのである。 In general, since the amount of reflected light varies depending on the reflection characteristics of the measurement object, when the rising timing of the reflected signal S5b is determined as a timing exceeding a predetermined threshold, the reflected light enters the light receiving unit 5 at the same timing. However, the rise characteristic differs depending on the amount of light, and a slight error occurs. However, when the reflected signal S5b is differentiated and obtained as the center of gravity position of the positive side region, even if the amount of light is different, the values are almost equal. It is determined.
システム制御部71は、〔数2〕に示すように、第二メモリ729に記憶された基準光遅延時間Δt1と反射光遅延時間Δt2の差から算出される両信号間の遅延時間Δtに基づいて、〔数3〕に示す演算式により測定対象物までの距離Lを算出するとともに、そのときの走査角度検出部15からの信号入力に基づいて測定対象物の存在する方向を同定する。なお、〔数3〕のCは光速を示す。 As shown in [Equation 2], the system control unit 71 is based on the delay time Δt between both signals calculated from the difference between the reference light delay time Δt1 and the reflected light delay time Δt2 stored in the second memory 729. The distance L to the measurement object is calculated by the arithmetic expression shown in [Equation 3], and the direction in which the measurement object exists is identified based on the signal input from the scanning angle detection unit 15 at that time. Note that C in [Equation 3] indicates the speed of light.
測定光S2の発光強度は当該発光駆動信号のデューティ比及び発光素子の駆動電流により制御され、測定対象空間に設定された検出範囲内に存在する測定対象物からの反射光を確実に検出するために十分な発光強度に設定されているため、反射光の強度によっては受光部5の増幅回路が飽和してリニアな出力特性が得られない場合がある。つまり、微弱な反射光を十分に増幅するために、増幅回路のダイナミックレンジが入力スパンに対応できず、強い反射光に対して飽和するのである。 The light emission intensity of the measurement light S2 is controlled by the duty ratio of the light emission drive signal and the drive current of the light emitting element, so that the reflected light from the measurement object existing in the detection range set in the measurement object space can be detected reliably. Therefore, depending on the intensity of the reflected light, the amplifier circuit of the light receiving unit 5 may be saturated and a linear output characteristic may not be obtained. That is, in order to sufficiently amplify the weak reflected light, the dynamic range of the amplifier circuit cannot cope with the input span, and is saturated with respect to the strong reflected light.
図14に示すように、受光部5の増幅回路からの出力波形を観測すると、測定対象物からの反射光量が小さいときには、反射信号S5b1から反射信号S5b3に示すようにリニアに増幅されるが、測定対象物からの反射光量が大きいときには、反射信号S5b4から反射信号S5b6に示すように飽和して正確な波高値が出力されず、その出力が立ち下がるまでの時間が長くなる。このような場合には、算出された重心位置が本来あるべき重心位置とずれることとなり、測定対象物との距離Lが正確に算出できなくなる。 As shown in FIG. 14, when the output waveform from the amplifier circuit of the light receiving unit 5 is observed, when the amount of reflected light from the measurement object is small, the reflected signal S5b1 is amplified linearly as shown by the reflected signal S5b3. When the amount of reflected light from the measurement object is large, saturation occurs and the accurate peak value is not output as shown by the reflected signal S5b4 to reflected signal S5b6, and the time until the output falls becomes longer. In such a case, the calculated position of the center of gravity deviates from the position of the center of gravity that should be, and the distance L to the measurement object cannot be calculated accurately.
しかし、反射信号S5b4から反射信号S5b6のように出力が飽和したときには、その信号の積分値と反射光の受光光量に相関があることが見出されており、時間差検出部728により検出された重心位置に基づいて算出された距離Lを、当該積分値と予め設定された補正テーブル値に従って適切に補正することができる。 However, when the output is saturated like the reflected signal S5b4 to the reflected signal S5b6, it has been found that there is a correlation between the integrated value of the signal and the amount of received light of the reflected light, and the center of gravity detected by the time difference detection unit 728 The distance L calculated based on the position can be appropriately corrected according to the integral value and a preset correction table value.
そこで、反射光光量検出部726で当該積分値が算出され、その結果が第二メモリ729に格納される。反射光光量検出部726は、図12に示すように、ローパスフィルタ722を通過した出力信号S5のうち、基準信号S5aの次に現れる反射信号S5bに対して第一測定閾値L1と第二測定閾値L2の加算値を最初に超える直前のサンプリング値から第二測定閾値L2を最初に下回るサンプリング値までを積分範囲R2として積分処理する。積分処理に際して、積分範囲R2に対応する積分値から第二測定閾値L2以下の領域の積分値を減算することによりオフセット誤差を除去する。ここで、オフセット誤差を除去するために、積分範囲R2のサンプリング値から第二測定閾値L2を減算した値に対して積分することも可能である。 Therefore, the integrated value is calculated by the reflected light amount detection unit 726, and the result is stored in the second memory 729. As shown in FIG. 12, the reflected light amount detection unit 726 includes a first measurement threshold L1 and a second measurement threshold for the reflected signal S5b that appears next to the reference signal S5a in the output signal S5 that has passed through the low-pass filter 722. The integration process is performed with the integration range R2 from the sampling value immediately before first exceeding the addition value of L2 to the sampling value that first falls below the second measurement threshold L2. In the integration process, the offset error is removed by subtracting the integration value in the region below the second measurement threshold L2 from the integration value corresponding to the integration range R2. Here, in order to remove the offset error, it is also possible to integrate the value obtained by subtracting the second measurement threshold value L2 from the sampling value in the integration range R2.
システム制御部71は第二メモリ729に記憶された積分値を読み出して、予め設定された積分値と補正距離の関係を示す補正テーブル値に基づいて算出された距離Lを補正するのである。 The system control unit 71 reads the integral value stored in the second memory 729 and corrects the distance L calculated based on a correction table value indicating the relationship between the preset integral value and the correction distance.
基準光路を介して検出される基準光S3の強度は、受光部5により光電変換された基準信号の波高値が想定される測定対象物からの反射光の平均光量よりも小さい値、本実施形態では平均光量の1/10程度の値になるように調整されている。具体的には、上述の第1から第6の実施形態で説明した光ファイバ6、44の径や配置、反射部材22、52、62による基準光の反射率、或いは第3の実施形態で説明した貫通孔32に配置する減光フィルタ等、光学素子の特性や配置等が調整されている。 The intensity of the reference light S3 detected through the reference optical path is a value smaller than the average light quantity of the reflected light from the measurement object in which the peak value of the reference signal photoelectrically converted by the light receiving unit 5 is assumed. Then, it is adjusted so that it becomes a value of about 1/10 of the average light quantity. Specifically, the diameter and arrangement of the optical fibers 6 and 44 described in the first to sixth embodiments, the reflectance of the reference light by the reflecting members 22, 52 and 62, or the third embodiment. The characteristics and arrangement of optical elements such as a neutral density filter arranged in the through-hole 32 are adjusted.
つまり、受光部5で検出される基準信号S5aの最大信号レベルが所定の第一閾値B1以下となるように基準光S3の光量が予め調整され、反射光と識別できるように構成されている。基準光の最大信号レベルが第一閾値B1、つまり、測定対象物からの反射光の想定最小信号レベルより低い値以下になるように予め調整されるので、測定光の出力タイミングに同期した所定のタイミングにおいて受光部5で検出される信号レベルが第一閾値B1より高いときには、走査式測距装置の近傍に測定対象物が位置すると判断することができ、誤った演算を行なうことなく、適切に対応することができるように構成されている。以下、詳述する。 That is, the light amount of the reference light S3 is adjusted in advance so that the maximum signal level of the reference signal S5a detected by the light receiving unit 5 is equal to or less than the predetermined first threshold value B1, and can be distinguished from the reflected light. Since the maximum signal level of the reference light is adjusted in advance so as to be equal to or less than the first threshold value B1, that is, a value lower than the assumed minimum signal level of the reflected light from the measurement object, a predetermined value synchronized with the output timing of the measurement light When the signal level detected by the light receiving unit 5 is higher than the first threshold value B1 at the timing, it can be determined that the measurement object is located in the vicinity of the scanning distance measuring device, and it can be appropriately performed without performing an erroneous calculation. It is comprised so that it can respond. Details will be described below.
基準光光量検出部727は、ローパスフィルタ722を通過した出力信号S5のうち、第一測定閾値L1と第二測定閾値L2の加算値を最初に超える直前のサンプリング値から第二測定閾値L2を最初に下回るサンプリング値までを基準信号S5aと認識し、その間の最大値からオフセット値である第二測定閾値L2を減算した値が第一閾値B1より小さいか否か、さらには第一閾値B1より低く設定された第二閾値B2より小さいか否かを判別する基準光光量判別部を備えている。 The reference light quantity detection unit 727 first calculates the second measurement threshold L2 from the sampling value immediately before the first addition of the first measurement threshold L1 and the second measurement threshold L2 in the output signal S5 that has passed through the low-pass filter 722. Up to a sampling value lower than 1 is recognized as the reference signal S5a, and whether or not a value obtained by subtracting the second measurement threshold value L2 that is an offset value from the maximum value therebetween is smaller than the first threshold value B1, or even lower than the first threshold value B1. A reference light amount determination unit that determines whether or not the second threshold value B2 is smaller than the set second threshold B2 is provided.
基準光光量判別部で基準信号S5aが第二閾値B2より小さいと判別されたときに、投光部3または受光部5を構成する光源や受光素子等の部品または光学系に何らかの支障を来たしていると判断して故障情報を第二メモリ729に格納する。システム制御部71は第二メモリ729に記憶された故障情報を読み出すと、システムに障害が発生した旨の情報を外部に報知する。具体的には、LEDで構成される故障モニタが点灯され、或いはアラームが鳴動され、また或いは接続されている外部機器に故障信号が出力される。つまり、基準光光量判別部により自己診断部が構成されている。 When the reference light quantity discriminating unit determines that the reference signal S5a is smaller than the second threshold value B2, the light source or the light receiving element constituting the light projecting unit 3 or the light receiving unit 5 has some trouble or an optical system. The failure information is stored in the second memory 729. When the system control unit 71 reads the failure information stored in the second memory 729, the system control unit 71 notifies the outside of the information that a failure has occurred in the system. Specifically, a failure monitor composed of LEDs is turned on or an alarm is sounded, or a failure signal is output to a connected external device. That is, a self-diagnosis unit is configured by the reference light quantity determination unit.
基準光光量検出部727には、基準光光量判別部で基準信号S5aが第二閾値B2より大きく且つ第一閾値B1より小さい正常な値であると判別されたときに、測定光の出力タイミングから基準信号S5aの立下りまでの波形データを、測定光の出力タイミングに同期した基準光の特性データとして記憶する基準信号波形データ記憶部727aを備えている。 The reference light amount detection unit 727 detects the output timing of the measurement light when the reference light amount determination unit determines that the reference signal S5a is a normal value larger than the second threshold B2 and smaller than the first threshold B1. A reference signal waveform data storage unit 727a that stores waveform data up to the fall of the reference signal S5a as reference light characteristic data synchronized with the output timing of the measurement light is provided.
さらに、基準光光量検出部727には、基準光光量判別部で正常と判断された基準信号S5aと過去に基準信号波形データ記憶部727aに記憶されている基準信号S5aとを平均処理した平均波形データを特性データとして生成し、基準信号波形データ記憶部727aに記憶する平均波形生成部と、基準光光量判別部で正常と判断された基準信号S5aと過去に基準信号波形データ記憶部727aに記憶されている基準信号S5aとを累積加算処理した累積加算波形データを特性データとして生成し、基準信号波形データ記憶部727aに記憶する累積加算波形生成部を備えている。 Further, the reference light quantity detection unit 727 averages an average waveform obtained by averaging the reference signal S5a determined to be normal by the reference light quantity determination unit and the reference signal S5a stored in the reference signal waveform data storage unit 727a in the past. The data is generated as characteristic data and stored in the reference signal waveform data storage unit 727a, the reference signal S5a determined to be normal by the reference light quantity determination unit, and the reference signal waveform data storage unit 727a in the past. A cumulative addition waveform generation unit that generates cumulative addition waveform data obtained by cumulative addition processing with the reference signal S5a that has been generated as characteristic data and stores the characteristic data in the reference signal waveform data storage unit 727a is provided.
累積加算波形生成部で求められる累積加算波形データは、直近の過去数回の基準信号波形データが加算されるように構成されており、これにより反射信号に対して低レベルの基準信号であっても、上述の微分処理や重心演算処理に十分なレベルの基準信号とすることができる。例えば、基準信号の波高値が反射光の平均光量の1/10程度の値になるように調整されている本実施例では、直近の10回の基準信号波形データを加算するように構成している。 The cumulative added waveform data obtained by the cumulative added waveform generation unit is configured such that the most recent past reference signal waveform data is added, so that it is a low level reference signal relative to the reflected signal. Also, a reference signal having a level sufficient for the above-described differential processing and centroid calculation processing can be obtained. For example, in the present embodiment in which the peak value of the reference signal is adjusted to be a value of about 1/10 of the average amount of reflected light, the latest 10 reference signal waveform data are added. Yes.
平均波形生成部で求められる平均波形データの累積平均回数は特に制限されるものではなく、過去の単位走査毎、或いは数十走査毎、さらには数百回から数千回等、任意に設定することができる。 The cumulative average number of average waveform data obtained by the average waveform generator is not particularly limited, and can be arbitrarily set every past unit scan, every tens of scans, or even hundreds to thousands of times. be able to.
図13に示すように、走査式測距装置の近傍に測定対象物が位置すると、基準信号S5aに反射信号S5bが重畳して信号レベルが第一閾値B1より高くなる。このような場合に、微分処理部724で反射信号S5bが微分処理されると、同図に示す基準信号S5aに対する微分波形(図中、太い実線で示す)の影響により正確な重心位置が求められず、時間差検出部728により正確な時間差が検出されなくなる。 As shown in FIG. 13, when the measurement object is positioned in the vicinity of the scanning distance measuring device, the reflected signal S5b is superimposed on the reference signal S5a, and the signal level becomes higher than the first threshold value B1. In such a case, when the reflected signal S5b is differentiated by the differentiation processing unit 724, an accurate center of gravity position is obtained due to the influence of the differentiated waveform (indicated by a thick solid line) on the reference signal S5a shown in the figure. Therefore, the time difference detection unit 728 does not detect an accurate time difference.
そこで、基準光光量判別部で基準信号S5aの信号レベルが第一閾値B1以上であると判別されると、微分処理部724及び時間差検出部728に測定対象物が近距離に存在する旨の信号が出力されるように構成されている。 Therefore, if the reference light quantity determination unit determines that the signal level of the reference signal S5a is equal to or higher than the first threshold value B1, the signal indicating that the measurement object exists at a short distance in the differentiation processing unit 724 and the time difference detection unit 728. Is output.
微分処理部724では、当該信号が入力されると、基準信号と反射信号が重畳した出力信号S5から基準信号波形データ記憶部727aに記憶された基準信号S5aの累積平均波形データを減算して真の反射信号S5bを生成する。そして、基準信号波形データ記憶部727aに記憶された過去の基準信号S5aの累積加算波形データと、当該真の反射信号S5bの夫々に対して微分処理が実行される。 When the signal is input, the differential processing unit 724 subtracts the accumulated average waveform data of the reference signal S5a stored in the reference signal waveform data storage unit 727a from the output signal S5 in which the reference signal and the reflected signal are superimposed. The reflection signal S5b is generated. Then, a differentiation process is performed on each of the accumulated waveform data of the past reference signal S5a stored in the reference signal waveform data storage unit 727a and the true reflected signal S5b.
図13に示すように、時間差検出部728では、微分処理部724から入力された夫々の微分信号に対する重心演算処理を行ない、測定光の出力タイミング、つまりトリガ信号の出力タイミングを基準として、基準信号S5aの累積加算波形データに対する基準光遅延時間Δt1、及び、真の反射信号S5bに対する反射光遅延時間Δt2を算出して第二記憶部729に記憶する。 As shown in FIG. 13, the time difference detection unit 728 performs a centroid calculation process on each differential signal input from the differential processing unit 724, and uses the output timing of the measurement light, that is, the output timing of the trigger signal as a reference signal. The reference light delay time Δt1 for the cumulative added waveform data of S5a and the reflected light delay time Δt2 for the true reflected signal S5b are calculated and stored in the second storage unit 729.
システム制御部71は、第二メモリ729に記憶された基準光遅延時間Δt1と反射光遅延時間Δt2の差から算出される両信号間の遅延時間Δtに基づいて、上述の〔数3〕に示す演算式により測定対象物までの距離Lを算出するとともに、そのときの走査角度検出部15からの信号入力に基づいて測定対象物の存在する方向を同定する。 Based on the delay time Δt between both signals calculated from the difference between the reference light delay time Δt1 and the reflected light delay time Δt2 stored in the second memory 729, the system control unit 71 represents the above [Equation 3]. The distance L to the measurement object is calculated by an arithmetic expression, and the direction in which the measurement object exists is identified based on the signal input from the scanning angle detection unit 15 at that time.
このようにして、走査式測距装置の近傍に測定対象物が位置するときには、近傍に測定対象物が存在しないと判断された過去において基準信号波形データ記憶部727aに記憶された累積加算波形データに基づいて基準光遅延時間が算出され、反射信号S5bから基準信号波形データ記憶部727aに記憶された累積平均波形データが減算された真の反射信号に基づいて反射光遅延時間が算出されるので、測定対象物までの距離が正確に算出されるようになる。 In this way, when the measurement object is located in the vicinity of the scanning distance measuring device, the cumulative added waveform data stored in the reference signal waveform data storage unit 727a in the past when it is determined that there is no measurement object in the vicinity. Therefore, the reference light delay time is calculated, and the reflected light delay time is calculated based on the true reflection signal obtained by subtracting the accumulated average waveform data stored in the reference signal waveform data storage unit 727a from the reflection signal S5b. The distance to the measurement object is accurately calculated.
さらに、反射信号S5bが受光部5の増幅回路で飽和しているときには、上述の累積平均波形データの減算による補正処理では正確な反射信号S5bが得られないため、システム制御部71は、上述と同様に、反射光光量検出部726で算出された積分値と補正テーブル値に基づいて距離を補正する。このとき、反射光光量検出部726でも、反射信号S5bから累積平均波形データを減算した真の反射信号S5bに基づいて積分値を算出することにより、正確な補正が可能となる。 Further, when the reflected signal S5b is saturated in the amplifier circuit of the light receiving unit 5, the correction processing by the subtraction of the cumulative average waveform data cannot obtain the accurate reflected signal S5b. Similarly, the distance is corrected based on the integral value calculated by the reflected light amount detection unit 726 and the correction table value. At this time, the reflected light amount detection unit 726 can also perform accurate correction by calculating the integral value based on the true reflected signal S5b obtained by subtracting the cumulative average waveform data from the reflected signal S5b.
他の方法として、基準信号S5aが重畳した反射信号S5bの波形形状と基準信号S5aが重畳していない反射信号S5bの波形形状から反射信号S5bの波形形状を補正する補正テーブルを予め準備しておき、当該補正テーブルに基づいて基準信号S5aが重畳した反射信号S5bを補正するように構成してもよい。 As another method, a correction table for correcting the waveform shape of the reflected signal S5b from the waveform shape of the reflected signal S5b on which the reference signal S5a is superimposed and the waveform shape of the reflected signal S5b on which the reference signal S5a is not superimposed is prepared in advance. The reflection signal S5b on which the reference signal S5a is superimposed may be corrected based on the correction table.
つまり、反射信号S5bが飽和しているときには、図14に示すように、急峻に立ち上がるため、反射信号S5bの立ち上がり特性に基準信号S5aのなだらかな立ち上がり特性が含まれているときには、そのなだらかな立ち上がり部分を除去して、反射信号S5bの急峻な立ち上がり特性で波形を補間するのである。 That is, when the reflected signal S5b is saturated, as shown in FIG. 14, it rises sharply. Therefore, when the rising characteristic of the reflected signal S5b includes the gentle rising characteristic of the reference signal S5a, the gentle rising The portion is removed and the waveform is interpolated with the steep rise characteristic of the reflected signal S5b.
図15に示すように、基準信号S5aと反射信号S5bとが重畳するときに、補正せずにそのまま微分処理する場合には、測定対象物が実際の距離より短く検出される。従って、走査式測距装置を安全装置として使用する場合には、安全サイドに距離が検出されるので大きな不都合は無い。同図は、測定光が4nsec.のパルス光である場合に、600mmの位置で60mm程度短く検出されることを示すものである。 As shown in FIG. 15, when the reference signal S5a and the reflected signal S5b are superimposed, if the differentiation process is performed without correction, the measurement object is detected to be shorter than the actual distance. Therefore, when the scanning distance measuring device is used as a safety device, the distance is detected on the safety side, so that there is no major inconvenience. In the figure, the measurement light is 4 nsec. This indicates that the light is detected as short as about 60 mm at a position of 600 mm.
なお、上述の説明では、微分処理部724で、出力信号S5が基準信号S5aの累積平均波形データで補正された後に微分処理される例を説明したが、算出される距離が要求される精度を満たしている場合には、必ずしも反射信号S5bを累積平均波形データで補正処理する必要はなく、基準信号S5aが重畳された反射信号S5bそのものを微分処理するものであってもよい。 In the above description, the example in which the differential processing unit 724 performs differential processing after the output signal S5 is corrected with the cumulative average waveform data of the reference signal S5a has been described, but the accuracy with which the calculated distance is required is described. If it is satisfied, it is not always necessary to correct the reflected signal S5b with the accumulated average waveform data, and the reflected signal S5b itself on which the reference signal S5a is superimposed may be differentiated.
また、基準光光量判別部で、特定の走査角にあるときのみ基準信号S5aが第一閾値B1より大きいと判別されるような場合や、基準信号S5aが第一閾値B1より大きいが、その後反射信号S5bが検出されるような場合には、ハウジング2に設けられた円環状の透光窓2a1の汚れにより測定光が透光窓2a1から反射していると判断して、透光窓2a1のクリーニングを促す旨の報知部を備えるものであってもよい。報知部は、LEDによる表示、アラームの鳴動等、適宜構成すればよい。 Further, when the reference light quantity determination unit determines that the reference signal S5a is larger than the first threshold B1 only when the reference light angle is at a specific scanning angle, or the reference signal S5a is larger than the first threshold B1, but is reflected thereafter. When the signal S5b is detected, it is determined that the measurement light is reflected from the translucent window 2a1 due to the dirt of the annular translucent window 2a1 provided in the housing 2, and the light of the translucent window 2a1 is determined. You may provide the alerting | reporting part to the effect of prompting cleaning. What is necessary is just to comprise an alerting | reporting part suitably, such as a display by LED, an alarm ringing.
以上説明した信号処理手順を図16に基づいて整理する。トリガ信号S1に同期して測定光S2が出力され、基準光及び反射光が受光部5にて検出され、AD変換器73でデジタルの基準信号及び反射信号に変換されて第一メモリ721に格納され、信号検出フェーズが終了する。第一メモリ721には、トリガ信号S1以降の受光部5の出力波形がサンプリングタイミングに応じて時系列に記憶されているため、メモリアドレスをカウントすることにより時間経過を把握することができる。 The signal processing procedure described above is organized based on FIG. The measurement light S2 is output in synchronization with the trigger signal S1, the reference light and the reflected light are detected by the light receiving unit 5, converted into a digital reference signal and a reflected signal by the AD converter 73, and stored in the first memory 721. This completes the signal detection phase. Since the output waveform of the light receiving unit 5 after the trigger signal S1 is stored in the first memory 721 in time series according to the sampling timing, the time passage can be grasped by counting the memory address.
第一フェーズが終了すると、基準光光量検出部727により第一メモリ721に格納された基準信号が適正な光量レベルであるか否かが判断され、適正であれば(第一閾値B1以下で第二閾値B2より大のとき)平均波形データ及び累積加算波形データが更新されて基準信号波形データ記憶部727aに格納され、反射信号に対して微分処理部724で微分処理され、時間差検出部728で微分波形に基づく重心演算が行なわれて反射光遅延時間Δt2が算出され、反射光遅延時間Δt2が第二メモリ729に格納されて、第二フェーズが終了する。 When the first phase is completed, the reference light amount detection unit 727 determines whether or not the reference signal stored in the first memory 721 is an appropriate light amount level. The average waveform data and the cumulative addition waveform data are updated and stored in the reference signal waveform data storage unit 727a, the reflected signal is differentiated by the differentiation processing unit 724, and the time difference detection unit 728 is used. The center of gravity calculation based on the differential waveform is performed to calculate the reflected light delay time Δt2, the reflected light delay time Δt2 is stored in the second memory 729, and the second phase ends.
なお、第二イフェーズで、基準光光量検出部727により基準信号が適正な光量レベルより異常に低いと判断されると(第二閾値B2より小のとき)平均波形データ等が更新処理されず、代わりに故障情報が第二メモリ729に格納され、適正な光量レベルより高いと判断されると(第一閾値B1より大のとき)平均波形データ等が更新処理されず、代わりに測定信号から過去の平均波形データが減算処理される。 In the second phase, when the reference light amount detection unit 727 determines that the reference signal is abnormally lower than the appropriate light amount level (when smaller than the second threshold B2), the average waveform data or the like is not updated, Instead, the failure information is stored in the second memory 729, and when it is determined that it is higher than the appropriate light amount level (when larger than the first threshold value B1), the average waveform data or the like is not updated, and instead the past from the measurement signal The average waveform data is subtracted.
第二フェーズが終了すると、基準信号波形データ記憶部727aに格納された累積加算波形データが微分処理部724に読み込まれて、基準信号に対する微分処理が行なわれ、時間差検出部728で微分波形に基づく重心演算が行なわれて基準光遅延時間Δt1が算出され、基準光遅延時間Δt1が第二メモリ729に格納される。システム制御部71により第二メモリ729に格納された基準光遅延時間Δt1及び反射光遅延時間Δt2の差分演算が行なわれて測定対象物までの距離が算出され、必要に応じて補正処理が施されて第三フェーズが終了する。 When the second phase is completed, the cumulative added waveform data stored in the reference signal waveform data storage unit 727a is read into the differentiation processing unit 724, the differentiation processing is performed on the reference signal, and the time difference detection unit 728 is based on the differentiated waveform. The center of gravity calculation is performed to calculate the reference light delay time Δt 1, and the reference light delay time Δt 1 is stored in the second memory 729. A difference between the reference light delay time Δt1 and the reflected light delay time Δt2 stored in the second memory 729 is calculated by the system control unit 71 to calculate the distance to the measurement object, and correction processing is performed as necessary. This completes the third phase.
第一フェーズから第三フェーズまでの演算処理がトリガ信号S1の周期内で実行されるのである。 The arithmetic processing from the first phase to the third phase is executed within the cycle of the trigger signal S1.
以上説明したように、本発明による走査式測距装置では、基準光路を介して得た基準信号により測定対象物までの距離を正確に検出することを可能としながらも、投光部からの測定光を周囲360度に連続して走査することができるようになった。 As described above, in the scanning distance measuring device according to the present invention, it is possible to accurately detect the distance to the measurement object based on the reference signal obtained through the reference optical path, while measuring from the light projecting unit. The light can be continuously scanned at 360 degrees around.
以下、別の実施形態を説明する。上述の実施形態では、受光部で検出される基準光の信号レベルが第一閾値以下の適正値であるときに、微分処理部724において、基準信号に対する微分処理が今回の基準光と基準信号波形データ記憶部727aに記憶された過去の基準光の信号波形との累積加算波形に対して行なわれるものを説明したが、基準光の光量レベルの設定が極端に低くない場合には、AD変換された生データに対して微分処理が行なわれるように構成するものであってもよい。また、今回の基準光と基準信号波形データ記憶部727aに格納された過去の基準光の信号波形との平均波形に対して微分処理が行なわれるように構成するものであってもよい。生データまたは平均波形のレベルが低いときには、各信号値を定数倍する増幅演算を行なった信号波形に対して微分処理が行なわれるようにしてもよい。 Hereinafter, another embodiment will be described. In the above-described embodiment, when the signal level of the reference light detected by the light receiving unit is an appropriate value that is equal to or less than the first threshold value, the differentiation processing for the reference signal is performed in the differentiation processing unit 724 by the current reference light and the reference signal waveform. The description has been given of what is performed on the cumulative addition waveform with the signal waveform of the past reference light stored in the data storage unit 727a. However, when the setting of the light amount level of the reference light is not extremely low, AD conversion is performed. The raw data may be configured to be differentiated. Further, the differential processing may be performed on the average waveform of the current reference light and the signal waveform of the past reference light stored in the reference signal waveform data storage unit 727a. When the level of the raw data or the average waveform is low, differentiation processing may be performed on the signal waveform that has been subjected to the amplification operation for multiplying each signal value by a constant.
さらに、システム制御部71が距離を算出する際に、第二メモリ729に記憶された過去の基準光遅延時間と今回の基準光遅延時間との平均値である平均遅延時間を真の基準光遅延時間として採用して、基準信号の平均遅延時間と反射光遅延時間に基づいて距離が算出されるように構成してもよい。このとき平均演算に採用するデータ数は特に制限されるものではない。 Further, when the system control unit 71 calculates the distance, an average delay time that is an average value of the past reference light delay time stored in the second memory 729 and the current reference light delay time is set as a true reference light delay. The distance may be calculated based on the average delay time of the reference signal and the reflected light delay time. At this time, the number of data employed for the average calculation is not particularly limited.
同様に、上述した実施形態では、基準信号が第一閾値B1よりも大であるときに、基準信号波形データ記憶部727aに格納された過去の基準信号の累積加算波形に基づいて基準光遅延時間が算出される例を説明したが、受光部で検出される基準光の信号レベルが第一閾値B1以下の適正な値であるときに、基準光の特性データが記憶部に記憶され、基準光の信号レベルが第一閾値B1より大となるときに、記憶部に記憶された過去の特性データに基づいて測定光の出力タイミングから基準光が検出されるまでの基準光遅延時間が求められるものであれば、必ずしも累積加算波形に基づいて基準光遅延時間が算出される必要が無い。 Similarly, in the above-described embodiment, when the reference signal is larger than the first threshold value B1, the reference optical delay time is based on the cumulative addition waveform of the past reference signal stored in the reference signal waveform data storage unit 727a. However, when the signal level of the reference light detected by the light receiving unit is an appropriate value not more than the first threshold value B1, the reference light characteristic data is stored in the storage unit, and the reference light is The reference light delay time until the reference light is detected from the output timing of the measurement light is obtained based on the past characteristic data stored in the storage unit when the signal level of the signal becomes larger than the first threshold value B1. If so, it is not always necessary to calculate the reference light delay time based on the cumulative addition waveform.
このような過去の特性データとしては、累積加算波形以外に、基準光の信号波形、信号波形の累積加算波形、基準光遅延時間、基準光遅延時間の平均遅延時間等を採用することができる。このときも必要な平均演算に採用するデータ数は特に制限されるものではない。 As such past characteristic data, in addition to the cumulative addition waveform, a reference light signal waveform, a signal waveform cumulative addition waveform, a reference light delay time, an average delay time of the reference light delay time, and the like can be employed. At this time, the number of data employed for the required average calculation is not particularly limited.
なお、上述の実施形態において、基準信号と測定信号の立上りタイミングを、微分信号の正側領域の重心位置により求めるものを説明したが、立上りタイミングを求めるための演算は、これに限るものではなく、例えば双方の信号S5a、S5bの立ち上がり部分の時間軸上での重心位置を算出する方法や、双方の信号の立ち上がり部分を直線近似または多項式近似して、その近似線と出力信号S5のオフセットレベルとの交点の位置を算出する方法等を採用することができる。 In the above-described embodiment, the description has been given of the case where the rising timing of the reference signal and the measurement signal is obtained from the position of the center of gravity of the positive side region of the differential signal. However, the calculation for obtaining the rising timing is not limited thereto. For example, a method of calculating the position of the center of gravity of the rising portions of both signals S5a and S5b on the time axis, or a linear approximation or polynomial approximation of the rising portions of both signals, and the offset level between the approximate line and the output signal S5 For example, a method of calculating the position of the intersection with the can be adopted.
上述した実施形態は、本発明の一実施例であり、形状、材料、回路構成等各部の具体的な構成は、本発明による作用効果を奏する範囲において適宜変更設計できることはいうまでもない。 The embodiment described above is an example of the present invention, and it is needless to say that the specific configuration of each part such as shape, material, circuit configuration, and the like can be changed and designed as appropriate within the scope of the effects of the present invention.
1 走査式測距装置
2 ハウジング
3 投光部
4 走査部
5 受光部
6 光ファイバ
8 回転体
9 投光ミラー
10 受光ミラー
11 モータ
15 走査角度検出部
21 走査式測距装置
22 反射部材
31 走査式測距装置
32 貫通孔
41 走査式測距装置
42 ミラー
43 走査部
44 光ファイバ
45a 光学レンズ
45b 光学レンズ
46 回転体
47 投受光ミラー
48 モータ
51 走査式測距装置
52 反射部材
61 走査式測距装置
62 反射部材
70 信号処理回路
71 システム制御部
72 信号処理部
73 AD変換器
74 モータ制御回路
721 第一メモリ
722 ローパスフィルタ
723 パルス信号生成部
724 微分処理部
725 閾値設定部
726 反射光光量検出部
727 基準光光量検出部
727a基準信号波形データ記憶部
729 第二メモリ
DESCRIPTION OF SYMBOLS 1 Scanning distance measuring device 2 Housing 3 Light projection part 4 Scanning part 5 Light receiving part 6 Optical fiber 8 Rotating body 9 Light projection mirror 10 Light reception mirror 11 Motor 15 Scan angle detection part 21 Scanning distance measuring device 22 Reflecting member 31 Scanning type Distance measuring device 32 Through hole 41 Scanning distance measuring device 42 Mirror 43 Scanning portion 44 Optical fiber 45a Optical lens 45b Optical lens 46 Rotating body 47 Projecting / receiving mirror 48 Motor 51 Scanning distance measuring device 52 Reflecting member 61 Scanning distance measuring device 62 reflection member 70 signal processing circuit 71 system control unit 72 signal processing unit 73 AD converter 74 motor control circuit 721 first memory 722 low-pass filter 723 pulse signal generation unit 724 differentiation processing unit 725 threshold setting unit 726 reflected light amount detection unit 727 Reference light quantity detection unit 727a Reference signal waveform data storage unit 729 Second memory
Claims (13)
前記測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路を備えると共に、前記測定光の出力タイミングに同期して前記受光部により検出される前記基準光と前記反射光の検出時間差に基づいて前記測定対象物までの距離を算出する演算部を備えている走査式測距装置。 A light projecting unit that outputs pulsed measurement light, a scanning unit that scans the measurement light output from the light projecting unit toward the measurement target space, and reflected light from the measurement target existing in the measurement target space A scanning rangefinder that measures a distance to the measurement object based on the reflected light detected by the light receiving unit,
A reference optical path for guiding a part of the measurement light as a reference light to the light receiving unit with a constant optical path length is provided, and the reference light and the reflected light detected by the light receiving unit in synchronization with an output timing of the measurement light A scanning distance measuring apparatus comprising a calculation unit that calculates a distance to the measurement object based on a difference in detection time between the two.
前記基準光路は、前記回転機構により回転し、前記投光ミラーで反射した前記測定光の一部を前記受光ミラーに導く導光部材を備えて構成されている請求項1記載の走査式測距装置。 The scanning unit includes a light projecting mirror that reflects the measurement light toward the measurement target space, a light receiving mirror that reflects reflected light from the measurement target toward the light receiving unit, the light projecting mirror, and the light projecting mirror. It is configured to include a rotation mechanism that rotates a light receiving mirror around an axis that connects the light projecting unit and the light receiving unit,
The scanning distance measuring device according to claim 1, wherein the reference optical path includes a light guide member that is rotated by the rotating mechanism and guides a part of the measurement light reflected by the light projecting mirror to the light receiving mirror. apparatus.
前記基準光路は、前記回転機構による回転軸心と同軸心に配置され、前記投光ミラーで反射した前記測定光の一部を前記受光ミラーに導く円環状の反射部材を備えて構成されている請求項1記載の走査式測距装置。 The scanning unit includes a light projecting mirror that reflects the measurement light toward the measurement target space, a light receiving mirror that reflects reflected light from the measurement target toward the light receiving unit, the light projecting mirror, and the light projecting mirror. It is configured to include a rotation mechanism that rotates a light receiving mirror around an axis that connects the light projecting unit and the light receiving unit,
The reference optical path includes an annular reflecting member that is arranged coaxially with the rotation axis of the rotation mechanism and guides a part of the measurement light reflected by the light projecting mirror to the light receiving mirror. 2. The scanning distance measuring device according to claim 1.
前記基準光路は、前記回転機構による回転軸心に沿って前記投光部から前記受光部に前記測定光の一部を導くように構成されている請求項1記載の走査式測距装置。 The scanning unit includes a light projecting mirror that reflects the measurement light toward the measurement target space, a light receiving mirror that reflects reflected light from the measurement target toward the light receiving unit, the light projecting mirror, and the light projecting mirror. It is configured to include a rotation mechanism that rotates a light receiving mirror around an axis that connects the light projecting unit and the light receiving unit,
2. The scanning distance measuring device according to claim 1, wherein the reference optical path is configured to guide a part of the measurement light from the light projecting unit to the light receiving unit along a rotation axis of the rotation mechanism.
前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、
前記基準光路は、前記測定光の一部を前記ミラーを介さずに前記受光部に導く導光部材を備えて構成されている請求項1記載の走査式測距装置。 A mirror that reflects the measurement light toward the scanning unit;
The scanning unit reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; It is configured with a rotation mechanism that rotates the light receiving mirror around a predetermined axis,
The scanning distance measuring device according to claim 1, wherein the reference optical path includes a light guide member that guides a part of the measurement light to the light receiving unit without passing through the mirror.
前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、
前記基準光路は、前記回転機構による回転軸心と同軸心に配置され、前記投受光ミラーで反射された前記測定光の一部を前記投受光ミラーに導く円環状の反射部材を備えて構成されている請求項1記載の走査式測距装置。 A mirror that reflects the measurement light toward the scanning unit;
The scanning unit reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; It is configured with a rotation mechanism that rotates the light receiving mirror around a predetermined axis,
The reference optical path includes an annular reflecting member that is arranged coaxially with the rotation axis of the rotation mechanism and guides a part of the measurement light reflected by the light projecting / receiving mirror to the light projecting / receiving mirror. 2. The scanning rangefinder according to claim 1.
前記走査部は、前記ミラーで反射された前記測定光を前記測定対象空間に向けて反射するとともに、前記測定対象物からの反射光を前記受光部に向けて反射する投受光ミラーと、前記投受光ミラーを所定の軸心周りに回転させる回転機構を備えて構成され、
前記基準光路は、前記回転機構により回転し、前記投受光ミラーで反射された前記測定光の一部を前記投受光ミラーに向けて反射する反射部材を備えて構成されている請求項1記載の走査式測距装置。 A mirror that reflects the measurement light toward the scanning unit;
The scanning unit reflects the measurement light reflected by the mirror toward the measurement target space and reflects the reflected light from the measurement target toward the light receiving unit; It is configured with a rotation mechanism that rotates the light receiving mirror around a predetermined axis,
The reference light path includes a reflecting member that is rotated by the rotating mechanism and reflects a part of the measurement light reflected by the light projecting / receiving mirror toward the light projecting / receiving mirror. Scanning distance measuring device.
前記測定光の一部を基準光として一定の光路長で前記受光部に導く基準光路を備えると共に、前記測定光の出力タイミングに同期して前記受光部により検出される前記基準光と前記反射光の検出時間差に基づいて測定対象物までの距離を算出する演算部を備え、
前記受光部で検出される前記基準光の最大信号レベルが所定の第一閾値以下となるように前記基準光の光量が予め調整され、前記反射光と識別可能に構成されている走査式測距装置。 A light projecting unit that outputs pulsed measurement light, a scanning unit that scans the measurement light output from the light projecting unit toward the measurement target space, and reflected light from the measurement target existing in the measurement target space A scanning rangefinder that measures a distance to a measurement object based on the reflected light detected by the light receiving unit,
A reference optical path for guiding a part of the measurement light as a reference light to the light receiving unit with a constant optical path length is provided, and the reference light and the reflected light detected by the light receiving unit in synchronization with an output timing of the measurement light A calculation unit that calculates the distance to the measurement object based on the detection time difference of
Scanning ranging that is configured such that the light amount of the reference light is adjusted in advance so that the maximum signal level of the reference light detected by the light receiving unit is equal to or less than a predetermined first threshold value, and can be distinguished from the reflected light. apparatus.
前記演算部は、前記基準光の信号レベルが前記第一閾値より大となるときに、前記記憶部に記憶された過去の特性データに基づいて得られる前記測定光の出力タイミングから前記基準光が検出されるまでの基準光遅延時間と、前記測定光の出力タイミングから前記反射光が検出されるまでの反射光遅延時間との時間差に基づいて前記測定対象物までの距離を算出する請求項8記載の走査式測距装置。 When the signal level of the reference light detected by the light receiving unit is less than or equal to the first threshold, the storage unit stores characteristic data obtained based on the current reference light,
When the signal level of the reference light is greater than the first threshold, the calculation unit determines that the reference light is derived from the output timing of the measurement light obtained based on past characteristic data stored in the storage unit. 9. The distance to the measurement object is calculated based on a time difference between a reference light delay time until detection and a reflected light delay time until the reflected light is detected from an output timing of the measurement light. The described scanning distance measuring device.
前記演算部は、前記基準光の信号レベルが前記第一閾値より大となるときに、当該信号波形から前記記憶部に記憶された累積平均波形を減算した信号を前記反射光として求める請求項9記載の走査式測距装置。 A storage unit that stores a cumulative average waveform of the signal waveform when the signal level of the reference light detected by the light receiving unit is equal to or lower than the first threshold;
The calculation unit obtains, as the reflected light, a signal obtained by subtracting a cumulative average waveform stored in the storage unit from the signal waveform when the signal level of the reference light becomes larger than the first threshold value. The described scanning distance measuring device.
前記演算部は、前記記憶部に記憶された累積加算波形、平均波形、または、平均遅延時間の何れかに基づいて得られる前記測定光の出力タイミングから前記基準光が検出されるまでの基準光遅延時間と、前記測定光の出力タイミングから前記反射光が検出されるまでの反射光遅延時間との時間差に基づいて前記測定対象物までの距離を算出する請求項8から10の何れかに記載の走査式測距装置。 When the signal level of the reference light detected by the light receiving unit is less than or equal to the first threshold, the cumulative addition waveform of the current reference light and the past signal waveform, the average of the current reference light and the past signal waveform A waveform or a storage unit that stores the average delay time between the reference light delay time of this time and the past reference light delay time,
The arithmetic unit is a reference light until the reference light is detected from the output timing of the measurement light obtained based on any of the accumulated addition waveform, the average waveform, or the average delay time stored in the storage unit 11. The distance to the measurement object is calculated based on a time difference between a delay time and a reflected light delay time until the reflected light is detected from an output timing of the measurement light. Scanning distance measuring device.
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