JP4057257B2 - Vehicle detection device - Google Patents
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- JP4057257B2 JP4057257B2 JP2001230801A JP2001230801A JP4057257B2 JP 4057257 B2 JP4057257 B2 JP 4057257B2 JP 2001230801 A JP2001230801 A JP 2001230801A JP 2001230801 A JP2001230801 A JP 2001230801A JP 4057257 B2 JP4057257 B2 JP 4057257B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、駐車場等で利用して好適な音響信号を利用した車両等の検出装置に関する。
【０００２】
【従来の技術】
現状の駐車場等での車両検出方法としては、駐車場ゲート近傍にループコイル、超音波センサー、光電管等を配設して使用した方法がある。
【０００３】
ループコイルによる車両検出方法は、地面に埋設したコイルが作る磁界に車両が入った時、ループコイルのインダクタンスの変化を検出して、車両の有無を判定している。
【０００４】
超音波センサーによる車両検出方法は、図１０に示すように、地面に向けて取付けられた超音波発信機ＳＮから発信された超音波が、車両ＯＭから反射して戻ってくるまでの時間を求めることで車両を検出している。ここで、車両が存在する時は、存在しない時よりも超音波が戻ってくるまでの時間が短い。
【０００５】
光電管によるセンサーは、発光器から受光器に向けて赤外線を飛ばす装置であり、光電管による方法は、これ等発光器と受光器との間に車両が入った時に赤外線が遮断されることを検出して、車両の有無を検出している。
【０００６】
【発明が解決しようとする課題】
しかし、上述した各車両検出方法には夫々以下の如き問題点を有していた。
（１） 上述したループコイルによる車両検出方法は、ループコイルの埋設費が掛かると共に、設置時の感度調整に手間がかかる、舗装路面の厚さ変化等の経年変化等などによる感度変化等の問題がある。
（２） 超音波による方法は、風やサーモクライン（温度逆転層）などの環境要因によって、超音波が戻るまでの時間に差が生じ、車両検出が失敗する恐れがある。
（３） 光電管による車両検出では、赤外線のオン、オフだけの検出方法であり、検出物体の大きさ等認識出来ず、車両なのか、それ以外の物なのかの区別が不可能である。また、定期的にレンズの掃除等のメンテナンスが必要、設置時の角度調整などのチューニングに手間が掛かるなどの問題がある。
【０００７】
そこで本発明の技術的課題は、埋設工事等が不要で風やサーモクライン（温度逆転層）などの環境要因の影響が無い安価にして、高性能な車両等の検出装置を提供することである。
【０００８】
【課題を解決するための手段】
上述の技術的課題を解決するために、本発明に係る車両等の検出装置は、前記請求項１に記載の如く、音響信号を発生する音響発信器を含む音響信号発信手段と、前記音響信号を受信する少なくとも３つの音響受信器を含む音響信号受信手段と、前記音響発信器からの音響信号が前記少なくとも３つの音響受信器に到達する時間の各時間差を求める到達時間差演算手段と、前記到達時間差に基づいて、前記音響信号発信手段と前記音響信号受信手段との間の音響信号経路上に存在する物体を検知する物体検知手段、及び、これ等各手段を制御するための演算処理装置とを備えて成る車両等の検出装置であって、上記演算処理装置によって制御される上記の到達時間差演算手段によって、上記少なくとも３つの音響受信器によって受信される音響信号のうち、２つの音響信号の到達時間差を相互相関関数により演算することにより、上記物体検知手段による上記音響信号経路上に存在する物体の検知を可能と成し、上記音響信号発信手段によって発信される音響信号を生成するに当って、上記の演算処理装置が、設置空間の音響特性に起因する音響信号の周波数成分が増幅、減衰する周波数帯域を把握するために、車両等の物体が存在しない時の上記音響信号発信手段より発信されたチャープ信号と、上記音響信号受信手段によって受信された信号間の伝達関数を求めて、白色雑音より当該伝達関数の出力により把握された設置空間の音響特性に起因して増幅、減衰する周波数帯域と、予想される騒音の周波数帯域を除去するためのデジタルフイルタ処理を行うと共に、上記物体の検知に当たって、上記の演算処理装置が、上記音響信号受信手段が受信した音響信号に対して、上記と同条件のデジタルフイルタ処理を行うことを特徴としている。
【０００９】
更に、本発明に係る車両等の検出装置は、前記請求項３に記載の如く、駐車場のカーゲートに、音響信号を発生する音響発信器を含む音響信号発信手段と、前記音響信号を受信する少なくとも３つの音響受信器を含む音響信号受信手段と、前記音響発信器からの音響信号が前記少なくとも３つの音響受信器に到達する時間の各時間差を求める到達時間差演算手段と、前記到達時間差に基づいて、前記音響信号発信手段と前記音響信号受信手段との間の音響信号経路上に存在する物体を検知する物体検知手段、及び、これ等各手段を制御するための演算処理装置とを設け、前記音響信号が前記音響発信器から前記音響受信器に到達するまでの到達時間差を求めることにより、前記カーゲート近傍に存在する車両を検出する車両等の検出装置であって、上記音響発信器と少くとも３つの前記音響受信器のうち、両端の受信器を除く少くとも１つを結ぶ仮想線が、通常ゲートが閉まった状態では車両の存在する可能性のないゲートバーの下で、且つ、ゲートバーと平行になるように配置され、上記演算処理装置によって制御される上記の到達時間差演算手段によって、上記少なくとも３つの音響受信器によって受信される音響信号のうち、２つの音響信号の到達時間差を相互相関関数により演算することにより、上記物体検知手段による上記音響信号経路上に存在する物体の検知を可能と成し、上記音響信号発信手段によって発信される音響信号を生成するに当って、上記の演算処理装置が、設置空間の音響特性に起因する音響信号の周波数成分が増幅、減衰する周波数帯域を把握するために、車両等の物体が存在しない時の上記音響信号発信手段より発信されたチャープ信号と、上記音響信号受信手段によって受信された信号間の伝達関数を求めて、白色雑音より当該伝達関数の出力により把握された設置空間の音響特性に起因して増幅、減衰する周波数帯域と、予想される騒音の周波数帯域を除去するためのデジタルフイルタ処理を行うと共に、上記物体の検知に当たっても、上記の演算処理装置が、上記音響信号受信手段が受信した音響信号をＡ／Ｄコンバータによって量子化したデジタル信号を取り込んで、生成したデジタル音響信号に対して、上記と同条件のデジタルフイルタ処理を行うことを特徴としている。
【００１０】
上述した各手段によれば、音響信号発生手段であるスピーカから音響信号を発信すると、スピーカと対向する側に設けられた音響信号受信手段である複数のマイクで音響信号を受信し、その信号をＡ／Ｄコンバータにより量子化して演算処理装置に送信する。演算処理装置で量子化した各マイクの受信信号のうち、任意の２組に関する相互相関関数を計算し、各マイクに音響信号が到達するまでの時間差をそれぞれ求める。
【００１１】
ゲートが閉まっている状態では、音響受信手段の少くとも３つのうち、両端の２つを除いたものの１つとスピーカを結ぶ線は、ゲートバーと平行に設置してあるため、この音響受信手段はスピーカの発信した音響を回析の影響を受けることなく受信することになる。従って、この受信手段を基準に考えることができる。
【００１２】
スピーカと各マイク間に何も物体が存在していない時（Ｔａ≒Ｔｃ時）の、音響信号が各マイクに到達するまでの時間差（Ｔａ−Ｔｂ及びＴｃ−Ｔｂ）を予め測定しておく。そして、Ｔａ−Ｔｂ、又はＴｃ−Ｔｂが変化し、且つ、Ｔａ≠Ｔｃとなった時は（図２のような状態、以下この図について説明する）、物体が存在すると判定し、Ｔａ−Ｔｂの変化量により物体の大きさを判定し、存在する物体が車両かそれ以外の物かの判別を行う。
【００１３】
Ｔａ−Ｔｂ、又は、Ｔｃ−Ｔｂが変化しても、Ｔａ≒Ｔｃ（物体が存在しない状態）となった場合は、気温の影響で時間差が変化したものと判断し、再度Ｔａ−Ｔｂ及びＴｃ−Ｔｂを測定し、次回からの基準時間差とする。
【００１４】
そして、上記音響信号を生成するに当たって、演算処理装置によって、上記音響信号発信手段より発信したチャープ信号と、上記音響信号受信手段で受信された信号間の伝達関数を求めて、白色雑音より当該伝達関数の出力により把握された設置空間の音響特性に起因して増幅、減衰する周波数帯域と、予想される騒音の周波数帯域を除去するためのデジタルフイルタ処理を行う。また、車両等の検出に当たっては、受信した音響信号にも上述したのと同じ条件のデジタルフイルタ処理を行って、雑音中から発信された音響信号をほぼ忠実に抽出する。
【００１５】
【発明の実施の形態】
以下に本発明に係る車両等の検出装置の実施の形態を図１から図１０を参照しながら説明する。図１と図２は本発明に係る車両検出装置の基本原理を示すもので、図１に於いて、ＳＰは音響源であるスピーカ、１Ａ，１Ｂ，１ＣはそれぞれスピーカＳＰに対向して配置された音響受信器であるマイク、ＳＡ，ＳＢ，ＳＣはそれぞれスピーカＳＰからマイク１Ａ，１Ｂ，１Ｃに到達する音響信号、ＴａはスピーカＳＰからマイク１Ａに音響信号ＳＡが到達する到達時間、ＴｂはスピーカＳＰからマイク１Ｂに音響信号ＳＢが到達する到達時間、ＴｃはスピーカＳＰからマイク１Ｃに音響信号ＳＣが到達する到達時間である。
【００１６】
図２に示すように、複数の（少くとも３つの）マイク１Ａ〜１ＣをスピーカＳＰと対向するように設置する。スピーカＳＰから発信した音響信号ＳＡ〜ＳＣが、車両ＭＣで回析（回り込むこと）して伝達距離が伸び、各マイク１Ａ〜１Ｃに音響信号ＳＡ〜ＳＣが到達するまでの時間Ｔａ〜Ｔｃに差が出ることを利用し、車両を検出する。
【００１７】
スピーカとマイクとの間に何も物体が存在していない時（Ｔａ≒Ｔｃ時）の、音響信号が各マイクに到達するまでの到達時間差（Ｔａ−Ｔｂ及びＴｃ−Ｔｂ）を予め測定しておく。そして、到達時間差Ｔａ−Ｔｂ又はＴｃ−Ｔｂが変化し、且つ、Ｔａ≠Ｔｃとなった時は（図２のような状態）、物体が存在すると判定し、Ｔａ−Ｔｂの変化量により物体の大きさを判定し、存在する物体が車両ＭＣかそれ以外の物かの判別を行う。
【００１８】
Ｔａ−Ｔｂ、又は、Ｔｃ−Ｔｂが変化しても、Ｔａ≒Ｔｃ（物体が存在しない状態）となった場合は、気温の影響で時間差が変化したものと判断し、再度到達時間差Ｔａ−Ｔｂ、及び、Ｔｃ−Ｔｂを測定し、次回からの基準時間差とする。
【００１９】
マイク１Ａ〜１Ｃは、量子化（アナログ→デジタル変換）手段としての（Ａ／Ｄコンバータ４（図５参照）を介して、演算処理装置１０（図５参照）と接続する。その演算処理装置１０で、各マイクに音響信号が到達するまでの到達時間差を相互相関関数により計測し、車両の有無を判定する。
【００２０】
相互相関関数とは、２つの信号データの類似している箇所を見つけ、２つの信号の到達時間にどの位の時間差があるかを求める関数である。図３は、相互相関関数の一例を示すもので、信号Ａに対して信号Ｂがどの位の時間差で遅れているかを求めている。信号Ａ，Ｂのそれぞれの波形データを以下の関数で表わす。即ち、信号Ａの時刻０からはじまる長さＮの波形をＡ0（ｎ）、信号Ｂの時刻ｋから始まる長さＮの波形をＢ0（ｎ）とすると、時刻ｋに於ける信号Ａと信号Ｂの相互相関関数Ｃｒｒは以下の通りとなる。
【数１】
【００２１】
音響車両検出器設置場所の音響特性を把握する手段として、車両等が存在しない環境下でチャープ信号（周波数が漸減又は漸増する信号）を音響化して放射し、これを各マイクで検出して、元信号に対する伝達関数を求めると共に、その伝達関数の出力が０（ｄＢ）に近い周波数帯：ｆωを把握する。伝達関数の出力（ｄＢ）の絶対値が大きいと、元信号が周波数環境の音響特性により変質しているため、各マイクで検出する信号間の相互相関関数の結果に対する信頼性が乏しくなる。
【００２２】
伝達関数とは、あるシステムの周波数特性を調査する手段の一つであり、システムに入力された信号の各周波数成分のパワーがそのシステムによりどの程度増幅、減衰されるかを、各周波数毎に調べる信号処理関数である。
【００２３】
音響信号が周囲の雑音に埋もれた場合、マイクで音響信号を受信したか否かの判断が不可能になるため、車のエンジン音や、人の話し声などの周波数領域から外れた音響信号でなければならない。また、音響信号は次の必要条件を満たしておれば、相互相関関数のピークが顕著に出力される。即ち、必要条件とは（１）一連の信号中のパワー変化が不規則であること。（２）一連の信号中において周波数変化が不規則であること。（３）周辺環境の音響特性により、各マイクに到達するまでに変質しないことである。
【００２４】
そこで、発信する信号は周波数とパワーが不規則に変化する一連の信号（白色雑音、周波数分析をすると観測可能な全ての周波数帯域で一様なパワー分布である。）に対し、上記伝達関数の出力により把握された設置空間の音響特性に起因して増幅、減衰する周波数帯域（伝達関数の出力が０ｄＢに近い周波数帯域以外の帯域）と、予想される周囲の雑音の周波数領域を除くためのデジタルフイルタ処理を行う。デジタルフイルタとは、信号に対しハードウエア、または、ソフトウエアにより信号を構成している周波数成分のうち、必要な周波数成分のみを抽出する信号処理を行うフイルタである。
【００２５】
そして、受信した音響信号にも上述した処理と同じ条件のデジタルフイルタ処理を行うことで、雑音中から発信した音響信号をほぼ忠実に抽出することができる。
【００２６】
図４は、デジタルフイルタ処理の動作フローを示す。白色雑音が発信すると、フイルタ処理に於いて、ステップＲ１で伝達関数０ｄＢ近傍の周波数域を抽出し、ステップＲ２で周囲の外乱信号の周波数域を除去して、音響信号を発信する。
【００２７】
図５は、物体の検出フローを示すもので、演算処理装置１０における音響信号発信手段５によって音響信号増幅手段であるアンプ２に音響信号を入力する。アンプ２によって増幅された音響信号により音響信号発生手段であるスピーカＳＰから音響信号が発生され、この音響信号はマイク１Ａ，１Ｂ，１Ｃに入力される。
【００２８】
マイクによって受信された音響信号はアンプ３により増幅されてＡ／Ｄコンバータ４に入力され、量子化される。演算処理装置１０では、ステップＳ１でＡ／Ｄコンバータ４によって量子化されたデジタル信号データを取り込んで、前述したデジタルフイルタ処理を行った後、ステップＳ２で相互相関関数演算を行い、ステップＳ３で物体有無判定手段６が時間差変化量により物体の概略の大きさを判定し、存在する物体が処理対象物体であるか否かを判定する。次にステップＳ４に進み、時間差が変化した時に物体が存在するか否かを判定する手段８により、音響信号の到達時間Ｔａ，Ｔｂの比較計算を行い、ステップＳ５で基準時間差（Ｔａ−Ｔｂ，Ｔｃ−Ｔｂ）を測定する。
【００２９】
図６は、車両検出の動作フローを示し、ステップＳ１０でスピーカとマイクとの間に物体が存在しない時の音響信号到達時間差（基準時間差）を測定し、次にステップＳ１１で音響信号を発信し、マイクでその音響信号を受信する。マイクで受信した音響信号はＡ／Ｄコンバータに入力され、ステップＳ１４で前記図５に示した演算処理装置１０に入力されたか否かを判断する。入力されておれば、ステップＳ１５で受信信号に対して、外乱信号の周波数領域を除去するために前述したデジタルフイルタ処理を行う。入力されていなければ、ステップＳ１６でシステム故障と判定する。次に、ステップＳ１７に進み、音響信号到達時間差に変化があるか否かを判断し、変化がなければ、ステップＳ１８で物体無しの検出を行う。変化があれば、ステップＳ１９に進み、到達時間Ｔａ≠Ｔｃであるか否かを判断する。Ｔａ≠Ｔｃでなければ、ステップＳ２０で基準時間差を測定してステップＳ１１に戻る。Ｔａ≠Ｔｃであれば、ステップＳ２１に進み、時間差の変化量から、物体は車両程度の大きさか否かを判断する。物体が車両程度の大きさでなければ、ステップＳ２２に進み、車両以外の物体（人、自転車等）の検出を行う。物体が車両程度の大きさであれば、ステップＳ２３で車両検出を行う。
【００３０】
図７は、本発明の車両等の検出装置をカーゲート近傍の車両検出に応用した実施例を示す。図７に於いて、２０はカーゲート、２０Ｔはゲートバー、２１はカーゲートに配置されたスピーカ、２２はアームキャッチャー、２３はアームキャッチャー２２の近傍に設けられた円弧状のマイク取付板、Ｍ１，Ｍ２，Ｍ３，Ｍ４，Ｍ５は、それぞれ、スピーカ２１に対向して取付板２３に設けられたマイクである。
【００３１】
図７に示すように、カーゲート本体にスピーカ２１を取付け、アームキャッチャー２２側に複数のマイクＭ１〜Ｍ５を取付ける。スピーカから発信した音響信号がマイクＭ１〜Ｍ５に到達するまでの到達時間差を求めることで、カーゲート２１の近傍の車両検出可能である。
【００３２】
スピーカ２１とマイクＭ１〜Ｍ５との間の距離は、図７に示すように全て等距離でも良い。等距離であれば、いかなる気温でも全てのマイクに同時に音響信号が到達するので、温度補正等の必要が無くなり、処理が簡潔になる。アームキャッチャー２２側に取付けているマイクの中で、ゲートバー真下に位置するマイクＭ３は、ゲートバー２０Ｔの真下に車両が存在するか否かを検出するためのもので、ゲート真下に車両が居た場合はゲートバー２０Ｔが降りないように制御する。
【００３３】
図８は上記実施例の動作を示すゲート制御用ブロック図であって、２０Ａは信号処理及び音響車両検出手段、２０Ｂは制御対象装置のアクション制御手段である。スピーカ２１からの音響信号はマイクＭ１，Ｍ２，Ｍ３に向けられ、マイクの音響信号はアンプ２４によって増幅された後に、Ａ／Ｄコンバータ２５に入力され、量子化される。量子化されたデータは手段２０Ａによって信号処理され、手段２０Ｂによってアクション制御し、制御対象装置によってゲート開、発券動作等が行われる。
【００３４】
即ち、図９の動作フローに示すように、ステップＳ３０で音響信号を発信し、この発信信号に基づいてステップＳ３１で物体が存在するか否かを判断し、ステップＳ３２で、物体は検出したい対象物程度の大きさか否かの判断を行う。物体が検出したい程度の大きさでなければ、ステップＳ３３に進み、対象物以外の物体を検出したと判断し、ステップＳ３０に戻る。ステップＳ３２で物体が対象物程度の大きさと判断すれば、ステップＳ３４に進み、音響検出器で制御する装置のゲート開、発券動作等のアクション開始を行う。その後、ステップＳ３５で物体がその場所から離れたか否かを判断し、離れておればアクションを終了する。
【００３５】
【発明の効果】
以上説明したように、本発明に係る車両等の検出装置は、音響信号を発生する音響発信器を含む音響信号発信手段と、前記音響信号を受信する少くとも３つの音響受信器を含む音響信号受信手段と、前記音響発信器からの音響信号が前記少くとも３つの音響受信器に到達する時間の各時間差を求める到達時間差演算手段、及び、前記到達時間差に基づいて、前記音響発信器と前記音響受信器との間の音響信号経路上に存在する物体を検知すると共に、発信する音響信号と受信した音響信号に対して同条件のデジタルフイルタ処理を行うことで、雑音中から発信された音響信号をほぼ忠実に抽出できるものであるから、埋設工事等が不要で、しかも、風やサーモクライン（温度逆転層）などの環境要因の影響が無い安価にして、高性能な車両等の検出装置を提供することができる。
【図面の簡単な説明】
【図１】 本発明の実施例による基本原理を示す説明図。
【図２】 本発明の実施例による基本原理を示す説明図。
【図３】 本発明で使用する相互相関関数波形の一例を示す説明図。
【図４】 白色雑音処理のフロー図。
【図５】 本発明の実施例による物体検知フロー図。
【図６】 本発明の実施例による車両検出の動作フロー図。
【図７】 本発明を駐車場管理装置に適用した実施例による説明図。
【図８】 図７の駐車場管理装置の動作フロー図。
【図９】 図７の駐車場管理装置の動作フロー図。
【図１０】 従来の車両検出方法の一例を示す説明図。
【符号の説明】
１Ａ，１Ｂ，１Ｃ マイク
４ Ａ／Ｄコンバータ
１０ 演算処理装置
２０ カーゲート
２０Ｔ ゲートバー
２１ スピーカ
２２ ゲートキャッチャー
ＳＰ スピーカ
ＭＣ 車両[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a detection device for a vehicle or the like that uses an acoustic signal suitable for use in a parking lot or the like.
[0002]
[Prior art]
As a vehicle detection method in a current parking lot or the like, there is a method in which a loop coil, an ultrasonic sensor, a phototube or the like is provided in the vicinity of a parking lot gate.
[0003]
In the vehicle detection method using a loop coil, when a vehicle enters a magnetic field created by a coil embedded in the ground, a change in the inductance of the loop coil is detected to determine the presence or absence of the vehicle.
[0004]
As shown in FIG. 10, the vehicle detection method using the ultrasonic sensor obtains the time until the ultrasonic wave transmitted from the ultrasonic transmitter SN attached to the ground is reflected from the vehicle OM and returned. The vehicle is detected. Here, when the vehicle exists, the time until the ultrasonic wave returns is shorter than when the vehicle does not exist.
[0005]
A phototube sensor is a device that emits infrared light from a light emitter toward a light receiver. The phototube method detects that the infrared light is blocked when a vehicle enters between the light emitter and the light receiver. The presence or absence of a vehicle is detected.
[0006]
[Problems to be solved by the invention]
However, each of the vehicle detection methods described above has the following problems.
(1) The above-described vehicle detection method using a loop coil requires a loop coil burying cost and takes time to adjust the sensitivity at the time of installation, and problems such as a sensitivity change due to a secular change such as a thickness change of a paved road surface There is.
(2) In the method using ultrasonic waves, there is a risk that vehicle detection may fail due to a difference in time until the ultrasonic waves return due to environmental factors such as wind and thermocline (temperature inversion layer).
(3) Vehicle detection using a phototube is a detection method that only turns on and off infrared rays, and the size of the detected object cannot be recognized, so that it is impossible to distinguish between a vehicle and other objects. In addition, there is a problem that maintenance such as cleaning of the lens is required regularly, and tuning such as angle adjustment at the time of installation is troublesome.
[0007]
Therefore, a technical problem of the present invention is to provide a high-performance detection device for a vehicle and the like that is inexpensive and does not need to be affected by environmental factors such as wind and thermocline (temperature inversion layer). .
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned technical problem, a detection device for a vehicle or the like according to the present invention includes an acoustic signal transmitting means including an acoustic transmitter for generating an acoustic signal, and the acoustic signal as described in claim 1. An acoustic signal receiving means including at least three acoustic receivers for receiving the signal, an arrival time difference calculating means for obtaining each time difference between the time when the acoustic signal from the acoustic transmitter reaches the at least three acoustic receivers, and the arrival An object detecting means for detecting an object existing on an acoustic signal path between the acoustic signal transmitting means and the acoustic signal receiving means based on the time difference, and an arithmetic processing device for controlling these means ; a detecting device for a vehicle or the like made comprises a sound by the arrival time difference calculating means controlled by said processing unit, which is received by said at least three acoustic receivers Among the signals, by calculating the cross-correlation function of the arrival time difference between the two acoustic signals, forms allow detection of an object present on the acoustic signal path by the object detecting means, emitted by the acoustic signal transmitter When generating the acoustic signal to be generated, there is an object such as a vehicle in order for the arithmetic processing unit to grasp the frequency band in which the frequency component of the acoustic signal due to the acoustic characteristics of the installation space is amplified and attenuated. a chirp signal transmitted from the audio signal transmitting means when not, seek a transfer function between signals received by said acoustic signal receiving means, acoustic been installation space grasped by the output of the transfer function from the white noise Digital filter processing is performed to remove the frequency band that is amplified and attenuated due to the characteristics and the expected frequency band of noise, and the object is detected. Against the above-mentioned processing apparatus, to the acoustic signal from which the acoustic signal received by the receiving means, is characterized by performing the digital filter processing of the same condition.
[0009]
Furthermore, the detection device for a vehicle or the like according to the present invention receives an acoustic signal transmitting means including an acoustic transmitter for generating an acoustic signal in a car gate of a parking lot, and the acoustic signal. an acoustic signal receiving means comprises at least three acoustic receivers, and the arrival time difference calculating means for determining a respective time difference between the time the acoustic signal reaches the said at least three acoustic receivers from the acoustic transmitter, based on the time difference of arrival Te, object detecting means for detecting an object existing on the acoustic signal path between the audio signal transmitting means and said acoustic signal receiving means, and a processing unit for controlling the like each means is provided, by determining the arrival time difference to said acoustic signal reaches the acoustic receiver from the acoustic transmitter, detector der of a vehicle or the like for detecting a vehicle existing in the Kerr gate near In addition, a virtual line connecting at least one of the acoustic transmitter and at least three of the acoustic receivers excluding the receivers at both ends is a gate bar in which there is no possibility that a vehicle is normally present when the gate is closed. Of the acoustic signals received by the at least three acoustic receivers by the arrival time difference computing means , which is arranged in parallel with the gate bar and controlled by the arithmetic processing unit. by calculating the cross-correlation function of the difference between the arrival times of the acoustic signals, forms allow detection of an object present on the acoustic signal path by the object detecting means, generates an acoustic signal emitted by the acoustic signal transmitter hitting to said arithmetic processing unit, a frequency component of the acoustic signal due to the acoustic characteristics of the installation space is amplified and grasp the frequency band to be attenuated To the chirp signal which objects such as a vehicle was originated from the acoustic signal transmitter of the absence, seeking a transfer function between signals received by said acoustic signal receiving means, the output of the transfer function from the white noise In addition to performing digital filter processing to remove the frequency band that is amplified and attenuated due to the acoustic characteristics of the installation space grasped by the above and the expected frequency band of noise, the above calculation is performed even when detecting the object. The processing device takes in a digital signal obtained by quantizing the acoustic signal received by the acoustic signal receiving means by an A / D converter, and performs digital filter processing under the same conditions as above on the generated digital acoustic signal . It is a feature.
[0010]
According to each means described above, when an acoustic signal is transmitted from a speaker which is an acoustic signal generating means, the acoustic signal is received by a plurality of microphones which are acoustic signal receiving means provided on the side facing the speaker, and the signal is received. It is quantized by the A / D converter and transmitted to the arithmetic processing unit. Of the received signals of each microphone quantized by the arithmetic processing unit, a cross-correlation function regarding any two sets is calculated, and a time difference until the acoustic signal reaches each microphone is obtained.
[0011]
In the state where the gate is closed, the line connecting the speaker to one of the at least three of the sound receiving means excluding the two at both ends and the speaker is installed in parallel with the gate bar. Will be received without being affected by diffraction. Therefore, this receiving means can be considered as a reference.
[0012]
A time difference (Ta−Tb and Tc−Tb) until an acoustic signal reaches each microphone when no object is present between the speaker and each microphone (when Ta≈Tc) is measured in advance. When Ta-Tb or Tc-Tb changes and Ta ≠ Tc (state as shown in FIG. 2, this figure will be described below), it is determined that an object exists, and Ta-Tb The size of the object is determined based on the amount of change, and it is determined whether the existing object is a vehicle or any other object.
[0013]
Even if Ta-Tb or Tc-Tb changes, if Ta≈Tc (state in which no object is present), it is determined that the time difference has changed due to the influence of the temperature, and Ta-Tb and Tc again. -Tb is measured and set as a reference time difference from the next time.
[0014]
Then, in order to generate the acoustic signal, by the processing unit to seek a chirp signal originating from the acoustic signal transmitter, the transfer function between signals received by said acoustic signal receiving means, the transmission from the white noise Digital filter processing is performed to remove the frequency band that is amplified and attenuated due to the acoustic characteristics of the installation space ascertained from the output of the function, and the expected frequency band of noise . When detecting a vehicle or the like, the received acoustic signal is subjected to digital filter processing under the same conditions as described above, and the acoustic signal transmitted from the noise is almost faithfully extracted.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a detection device for a vehicle or the like according to the present invention will be described below with reference to FIGS. 1 and 2 show the basic principle of the vehicle detection device according to the present invention. In FIG. 1, SP is a speaker as a sound source, and 1A, 1B, and 1C are arranged facing the speaker SP, respectively. The microphones SA, SB, and SC that are the acoustic receivers are acoustic signals that reach the microphones 1A, 1B, and 1C from the speaker SP, Ta is the arrival time that the acoustic signal SA reaches the microphone 1A from the speaker SP, and Tb is the speaker. The arrival time for the acoustic signal SB to reach the microphone 1B from the SP, and Tc is the arrival time for the acoustic signal SC to reach the microphone 1C from the speaker SP.
[0016]
As shown in FIG. 2, a plurality (at least three) of microphones 1A to 1C are installed so as to face the speaker SP. The acoustic signals SA to SC transmitted from the speaker SP are diffracted (turned around) by the vehicle MC to increase the transmission distance, and the difference in time Ta to Tc until the acoustic signals SA to SC reach the microphones 1A to 1C. The vehicle is detected by using that.
[0017]
When there is no object between the speaker and the microphone (when Ta≈Tc), the arrival time difference (Ta−Tb and Tc−Tb) until the acoustic signal reaches each microphone is measured in advance. deep. When the arrival time difference Ta−Tb or Tc−Tb changes and Ta ≠ Tc (the state shown in FIG. 2), it is determined that the object exists, and the amount of change of the object depends on the amount of change in Ta−Tb. The size is determined, and it is determined whether the existing object is the vehicle MC or any other object.
[0018]
Even if Ta−Tb or Tc−Tb changes, if Ta≈Tc (state in which no object is present), it is determined that the time difference has changed due to the temperature, and the arrival time difference Ta−Tb again. , And Tc−Tb are measured and set as a reference time difference from the next time.
[0019]
Mike 1A~1C via quantization as (analog → digital converter) means (A / D converter 4 (see FIG. 5), connected to the processing unit 10 (see FIG. 5). As processing unit 10 Thus, the arrival time difference until the acoustic signal reaches each microphone is measured by the cross-correlation function, and the presence or absence of the vehicle is determined.
[0020]
The cross-correlation function is a function that finds a location where two signal data are similar and determines how much time difference there is between the arrival times of the two signals. FIG. 3 shows an example of a cross-correlation function, which determines how much the signal B is delayed with respect to the signal A. Each waveform data of the signals A and B is expressed by the following function. That is, assuming that the waveform of length N starting from time 0 of signal A is A0 (n) and the waveform of length N starting from time k of signal B is B0 (n), signal A and signal B at time k. The cross-correlation function Crr is as follows.
[Expression 1]
[0021]
As a means to grasp the acoustic characteristics of the acoustic vehicle detector location, chirp signal in an environment where a vehicle or the like is not present (a signal frequency is gradually reduced or gradually increased) to radiate acoustically of which was detected by the microphone , together with obtaining the transfer function for the original signal, a frequency band close to the output of the transfer function 0 (dB): to understand the f [omega]. If the absolute value of the output (dB) of the transfer function is large, the reliability of the result of the cross-correlation function between the signals detected by each microphone becomes poor because the original signal is altered due to the acoustic characteristics of the frequency environment.
[0022]
A transfer function is one of the means for investigating the frequency characteristics of a system, and how much the power of each frequency component of the signal input to the system is amplified and attenuated by the system for each frequency. This is a signal processing function to check.
[0023]
If the sound signal is buried in the surrounding noise, it will be impossible to determine whether the sound signal has been received by the microphone, so the sound signal must be out of the frequency domain, such as car engine sound or human speech. I must. In addition, if the acoustic signal satisfies the following necessary conditions, the peak of the cross correlation function is remarkably output. That is, the necessary conditions are (1) the power change in a series of signals is irregular. (2) The frequency change is irregular in a series of signals. (3) Due to the acoustic characteristics of the surrounding environment, it does not change before reaching each microphone.
[0024]
Therefore, the signal originating frequency and power irregularly change a series of signals (a white noise, and uniform power distribution in all frequency bands observable frequency analysis.) To, the transfer function due to the acoustic characteristics of the installation space which is grasped by the output amplifier, and the attenuation frequency band (band output is other than a frequency band close to 0dB transfer function), for excluding the frequency range of ambient noise to be expected The digital filter processing is performed. A digital filter is a filter that performs signal processing for extracting only necessary frequency components from among frequency components constituting a signal by hardware or software.
[0025]
Then, by performing digital filter processing on the received acoustic signal under the same conditions as those described above , the acoustic signal transmitted from the noise can be extracted almost faithfully.
[0026]
FIG. 4 shows an operation flow of digital filter processing. When white noise is transmitted, in the filtering process, a frequency region near the transfer function 0 dB is extracted in step R1, and a frequency region of a surrounding disturbance signal is removed in step R2, and an acoustic signal is transmitted.
[0027]
FIG. 5 shows an object detection flow. An acoustic signal is input to the amplifier 2 which is an acoustic signal amplifying means by the acoustic signal transmitting means 5 in the arithmetic processing unit 10. An acoustic signal is generated from the speaker SP, which is an acoustic signal generating means, by the acoustic signal amplified by the amplifier 2, and this acoustic signal is input to the microphones 1A, 1B, and 1C.
[0028]
The acoustic signal received by the microphone is amplified by the amplifier 3 and input to the A / D converter 4 where it is quantized. The arithmetic processing unit 10 takes in the digital signal data quantized by the A / D converter 4 in step S1, performs the digital filter processing described above , performs a cross-correlation function calculation in step S2, and performs object processing in step S3. presence determining means 6 determines the size of the outline of the object by the time difference change amount present object determines whether the object to be treated. Next, the process proceeds to step S4, where the sound signal arrival times Ta and Tb are compared and calculated by means 8 for determining whether or not an object is present when the time difference changes. In step S5, the reference time difference (Ta-Tb, Tc−Tb) is measured.
[0029]
FIG. 6 shows an operation flow of vehicle detection. In step S10, an acoustic signal arrival time difference (reference time difference) is measured when no object is present between the speaker and the microphone, and then an acoustic signal is transmitted in step S11. The microphone receives the acoustic signal. The acoustic signal received by the microphone is input to the A / D converter, and it is determined in step S14 whether or not it has been input to the arithmetic processing unit 10 shown in FIG . If I is entered, for the received signal at step S15, it performs a digital filter process described above to remove the frequency range of the disturbance signal. If not input, it is determined in step S16 that there is a system failure. Next, it progresses to step S17, it is judged whether there is any change in the acoustic signal arrival time difference. If there is no change, the absence of an object is detected in step S18. If there is a change, the process proceeds to step S19 to determine whether or not the arrival time Ta ≠ Tc. If Ta ≠ Tc, the reference time difference is measured in step S20, and the process returns to step S11. If Ta ≠ Tc, the process proceeds to step S21, and it is determined from the amount of change in the time difference whether the object is about the size of the vehicle. If the object is not as large as the vehicle, the process proceeds to step S22, and an object (person, bicycle, etc.) other than the vehicle is detected. If the object is about the size of a vehicle, vehicle detection is performed in step S23.
[0030]
FIG. 7 shows an embodiment in which the detection device for a vehicle or the like of the present invention is applied to vehicle detection in the vicinity of the car gate. In FIG. 7, 20 is a car gate, 20T is a gate bar, 21 is a speaker arranged at the car gate, 22 is an arm catcher, 23 is an arc-shaped microphone mounting plate provided in the vicinity of the arm catcher 22, M1, M2, M3, M4, and M5 are microphones provided on the mounting plate 23 so as to face the speaker 21, respectively.
[0031]
As shown in FIG. 7, a speaker 21 is attached to the car gate body, and a plurality of microphones M1 to M5 are attached to the arm catcher 22 side. The vehicle in the vicinity of the car gate 21 can be detected by calculating the arrival time difference until the acoustic signal transmitted from the speaker reaches the microphones M1 to M5.
[0032]
The distance between the speaker 21 and the microphones M1 to M5 may all be equal as shown in FIG. If the distance is equal, the acoustic signal reaches all the microphones simultaneously at any temperature, so that there is no need for temperature correction and the processing is simplified. Among the microphones attached to the arm catcher 22 side, the microphone M3 located immediately below the gate bar is for detecting whether or not a vehicle is present directly below the gate bar 20T. Controls the gate bar 20T not to go down.
[0033]
FIG. 8 is a block diagram for gate control showing the operation of the above embodiment, in which 20A is signal processing and acoustic vehicle detection means, and 20B is action control means of the device to be controlled. The acoustic signal from the speaker 21 is directed to the microphones M1, M2, and M3. The acoustic signal of the microphone is amplified by the amplifier 24, and then input to the A / D converter 25 and quantized. The quantized data is signal-processed by means 20A, action-controlled by means 20B, and gate opening, ticketing operation, etc. are performed by the controlled device.
[0034]
That is, as shown in the operation flow of FIG. 9, an acoustic signal is transmitted in step S30, and based on this transmission signal, it is determined whether or not an object is present in step S31. In step S32, the object is an object to be detected. Judgment is made as to whether or not it is the size of an object. If the object is not large enough to be detected, the process proceeds to step S33, where it is determined that an object other than the object has been detected, and the process returns to step S30. If it is determined in step S32 that the object is about the size of the target, the process proceeds to step S34, where actions such as gate opening and ticketing operation of the device controlled by the acoustic detector are started. Thereafter, in step S35, it is determined whether or not the object has left the place. If the object has left, the action is terminated.
[0035]
【The invention's effect】
As described above, the detection device for a vehicle or the like according to the present invention includes an acoustic signal transmitting means including an acoustic transmitter that generates an acoustic signal, and an acoustic signal including at least three acoustic receivers that receive the acoustic signal. Receiving means, arrival time difference calculating means for obtaining each time difference between the time when the acoustic signal from the acoustic transmitter reaches the at least three acoustic receivers, and based on the arrival time difference, the acoustic transmitter and the By detecting an object that exists on the acoustic signal path with the acoustic receiver and performing digital filter processing under the same conditions on the transmitted acoustic signal and the received acoustic signal, Since the signal can be extracted almost faithfully, there is no need for burial work, etc., and there is no influence of environmental factors such as wind and thermocline (temperature inversion layer), and it is inexpensive and has high performance. It is possible to provide a detection apparatus.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a basic principle according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a basic principle according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing an example of a cross-correlation function waveform used in the present invention.
FIG. 4 is a flowchart of white noise processing.
FIG. 5 is an object detection flowchart according to an embodiment of the present invention.
FIG. 6 is an operation flowchart of vehicle detection according to the embodiment of the present invention.
FIG. 7 is an explanatory diagram of an embodiment in which the present invention is applied to a parking lot management apparatus.
FIG. 8 is an operation flowchart of the parking lot management apparatus of FIG.
FIG. 9 is an operation flowchart of the parking lot management apparatus of FIG. 7;
FIG. 10 is an explanatory diagram showing an example of a conventional vehicle detection method.
[Explanation of symbols]
1A, 1B, 1C Microphone 4 A / D converter
DESCRIPTION OF SYMBOLS 10 Arithmetic processing device 20 Car gate 20T Gate bar 21 Speaker 22 Gate catcher SP Speaker MC Vehicle
Claims (4)
上記演算処理装置によって制御される上記の到達時間差演算手段によって、上記少なくとも３つの音響受信器によって受信される音響信号のうち、２つの音響信号の到達時間差を相互相関関数により演算することにより、上記物体検知手段による上記音響信号経路上に存在する物体の検知を可能と成し、
上記音響信号発信手段によって発信される音響信号を生成するに当って、上記の演算処理装置が、設置空間の音響特性に起因する音響信号の周波数成分が増幅、減衰する周波数帯域を把握するために、車両等の物体が存在しない時の上記音響信号発信手段より発信されたチャープ信号と、上記音響信号受信手段によって受信された信号間の伝達関数を求めて、白色雑音より当該伝達関数の出力により把握された設置空間の音響特性に起因して増幅、減衰する周波数帯域と、予想される騒音の周波数帯域を除去するためのデジタルフイルタ処理を行うと共に、
上記物体の検知に当たって、上記の演算処理装置が、上記音響信号受信手段が受信した音響信号をＡ／Ｄコンバータによって量子化したデジタル信号を取り込んで、生成したデジタル音響信号に対して、上記と同条件のデジタルフイルタ処理を行うことを特徴とする車両等の検出装置。An acoustic signal transmitting means including an acoustic transmitter for generating an acoustic signal; an acoustic signal receiving means including at least three acoustic receivers for receiving the acoustic signal; and an acoustic signal from the acoustic transmitter is the at least three acoustic signals. and the arrival time difference calculating means for determining a respective time difference between the time to reach the receiver, on the basis of the arrival time difference, detects an object existing on the acoustic signal path between the audio signal transmitting means and said acoustic signal receiving means A detection device for a vehicle or the like comprising an object detection means and an arithmetic processing device for controlling each of these means ,
By the arrival time difference calculating means controlled by said processing unit, among the acoustic signals received by said at least three acoustic receivers, by calculating the cross-correlation function of the arrival time difference between the two acoustic signals, said form allowing the detection of an object present on the acoustic signal path by the object detecting means,
In generating the acoustic signal transmitted by the acoustic signal transmitting means , the arithmetic processing unit is configured to grasp the frequency band in which the frequency component of the acoustic signal due to the acoustic characteristics of the installation space is amplified and attenuated. a chirp signal object such as a vehicle was originated from the acoustic signal transmitter of the absence, seeking a transfer function between signals received by said acoustic signal receiving means, the output of the transfer function from the white noise Performs digital filter processing to remove the frequency band that is amplified and attenuated due to the acoustic characteristics of the grasped installation space and the expected frequency band of noise,
In the detection of the object, the arithmetic processing unit takes in a digital signal obtained by quantizing the acoustic signal received by the acoustic signal receiving unit with an A / D converter , and the same processing as described above is performed on the generated digital acoustic signal . A detection device for a vehicle or the like, which performs digital filter processing of conditions .
上記音響発信器と少くとも３つの前記音響受信器のうち、両端の受信器を除く少くとも１つを結ぶ仮想線が、通常ゲートが閉まった状態では車両の存在する可能性のないゲートバーの下で、且つ、ゲートバーと平行になるように配置され、上記演算処理装置によって制御される上記の到達時間差演算手段によって、上記少なくとも３つの音響受信器によって受信される音響信号のうち、２つの音響信号の到達時間差を相互相関関数により演算することにより、上記物体検知手段による上記音響信号経路上に存在する物体の検知を可能と成し、
上記音響信号発信手段によって発信される音響信号を生成するに当って、上記の演算処理装置が、設置空間の音響特性に起因する音響信号の周波数成分が増幅、減衰する周波数帯域を把握するために、車両等の物体が存在しない時の上記音響信号発信手段より発信されたチャープ信号と、上記音響信号受信手段によって受信された信号間の伝達関数を求めて、白色雑音より当該伝達関数の出力により把握された設置空間の音響特性に起因して増 幅、減衰する周波数帯域と、予想される騒音の周波数帯域を除去するためのデジタルフイルタ処理を行うと共に、
上記物体の検知に当たって、上記の演算処理装置が、上記音響信号受信手段が受信した音響信号をＡ／Ｄコンバータによって量子化したデジタル信号を取り込んで、生成したデジタル音響信号に対して、上記と同条件のデジタルフイルタ処理を行うことを特徴とする車両等の検出装置。An acoustic signal transmitting means including an acoustic transmitter for generating an acoustic signal in a car gate of a parking lot, an acoustic signal receiving means including at least three acoustic receivers for receiving the acoustic signal, and an acoustic signal from the acoustic transmitter There the arrival time difference calculating means for determining a respective time difference between the time to reach said at least three acoustic receivers, on the basis of the arrival time difference, on the acoustic signal path between the acoustic signal receiving means and said acoustic signal transmitter An object detection means for detecting an existing object and an arithmetic processing device for controlling each of these means are provided, and an arrival time difference until the acoustic signal reaches the acoustic receiver from the acoustic transmitter is obtained. Thus, a detection device such as a vehicle for detecting a vehicle existing in the vicinity of the car gate,
An imaginary line connecting at least one of the acoustic transmitters and at least three of the acoustic receivers except for the receivers at both ends is below the gate bar where the vehicle is not likely to exist when the gate is normally closed. in, and, are arranged parallel to the gate bar, by the arrival time difference calculating means controlled by said processing unit, among the acoustic signals received by said at least three acoustic receivers, two acoustic signals of by calculating the cross-correlation function of the arrival time difference, forms allow detection of an object present on the acoustic signal path by the object detecting means,
In generating the acoustic signal transmitted by the acoustic signal transmitting means , the arithmetic processing unit is configured to grasp the frequency band in which the frequency component of the acoustic signal due to the acoustic characteristics of the installation space is amplified and attenuated. a chirp signal object such as a vehicle was originated from the acoustic signal transmitter of the absence, seeking a transfer function between signals received by said acoustic signal receiving means, the output of the transfer function from the white noise grasping been installation space of amplifier due to the acoustic characteristics, it performs a frequency band for attenuating the digital filter processing for removing a frequency band of the noise to be expected,
In the detection of the object, the arithmetic processing unit takes in a digital signal obtained by quantizing the acoustic signal received by the acoustic signal receiving unit with an A / D converter , and the same processing as described above is performed on the generated digital acoustic signal . A detection device for a vehicle or the like, which performs digital filter processing of conditions .
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