JP3993694B2

JP3993694B2 - Directivity synthesis processing method

Info

Publication number: JP3993694B2
Application number: JP15248198A
Authority: JP
Inventors: 賢哉前田; 正吉田中
Original assignee: Japan Radio Co Ltd
Current assignee: Japan Radio Co Ltd
Priority date: 1998-06-02
Filing date: 1998-06-02
Publication date: 2007-10-17
Anticipated expiration: 2018-06-02
Also published as: JPH11346113A

Description

【０００１】
【発明の属する技術分野】
本発明は、超音波振動子アレイ、アレイアンテナ等の素子アレイにおける荷重／移相量分布を、所望の指向性パターン（仕様）に合致するよう決定する指向性合成処理方法に関する。
【０００２】
【従来の技術及びその問題点】
超音波振動子アレイは、概略、図５に示すように複数の振動子１０を空間的に分散配置し、各振動子１０を結合／分配部１２により接続した構成を有している。このアレイから超音波信号を送信する際には、図示しない送信機から結合／分配部１２に電気信号を入力する。結合／分配部１２は、この信号を各振動子１０毎に与えられている重み（荷重）に従い各振動子１０に分配し、さらに各振動子１０毎に与えられている移相量に従い移相させる。各振動子１０は、供給される電気信号を超音波信号に変換する。逆に、このアレイにて超音波信号を受信する際には、受信した超音波信号を各振動子１０にて電気信号に変換し、結合／分配部１２に供給する。結合／分配部１２は、この信号を上述の移相量に従い移相させ、更に上述の荷重に従い結合（加重加算）して図示しない受信機に供給する。なお、ここでは移相機能を結合／分配部１２の一部機能としているが、これは記載の簡略化のためである。
【０００３】
各振動子１０はそれぞれその構造等により定まる固有の指向性を有しているから、振動子１０の空間的配置を与えた上で、各振動子１０に係る荷重／移相量即ち超音波振動子アレイにおける荷重／移相量分布を定めることにより、超音波振動子アレイの指向性パターンを定めることができる。従って、各振動子１０の単体での指向性、各振動子１０の空間的配置、実現すべき指向性パターン（仕様）、及び荷重／移相量分布の初期値に基づき荷重／移相量分布を決定する、という作業によって、仕様を満たす指向性パターンを有する超音波振動子アレイを設計できる。また、複数のアンテナ素子を空間的に分散配置し結合／分配器にて結合した構成を有するアレイアンテナに関し、例えば「線形計画法による導波管スロットアレイアンテナの指向性合成」（原他、電子通信学会論文誌８３年７月、Ｖｏｌ．Ｊ６６−Ｂ、Ｎｏ．７）等に開示されているように、線形計画法を用いてその設計を行う手法が知られている。この手法は、計算機によるシミュレーションで実施できるため、超音波振動子アレイ、アレイアンテナ等の装置（本願では「素子アレイ」と総称する）を設計する作業を自動化するのに役立っている。
【０００４】
しかしながら、この手法には、全般的に自由度が欠ける、という問題点があった。まず、上述の手法で設計対象とすることができるのは、素子（超音波振動子、アンテナ素子等）の形状、配置、単体での指向性がいずれも所定の条件を満たす素子アレイに限られている。更に、与えることができる仕様（設計できる指向性パターン）にも制限があり、設計作業者が思いのままの仕様を与えることができない。更に、荷重／移相量分布が解に収束したことを検出するための条件（収束判定条件）を厳密に設定しなければならず、収束判定条件を変更する上で困難性がある。また、シミュレーションの過程に、適宜、処理に関する制約条件を挿入することも、困難である。加えて、荷重／移相量分布等の初期設定内容によって解が変化してしまうことがあるし、最適解ではなく局所解に到達してしまうこともある。
【０００５】
【発明の概要】
本発明の目的の一つは、素子の形状・配置・単体での指向性、設計できる指向性、収束判定条件、制約条件等の面で制約が緩く又は自由度が高い手法を提供することにある。本発明の目的の一つは、厳密な初期設定が不要で使い勝手がよく、最適解に到達しやすい手法を提供することにある。
【０００６】
本発明に係る指向性合成処理方法においては、指向性パターンに関するシミュレーションを実行する第１のステップ、微少修正の可否を判別し微少修正を実行する第２のステップ、及びシミュレーションの繰返し実行を終了するか否かの判定を行う第３のステップを、前提としている。
【０００７】
これらのステップのうち、第１のステップにおいては、第２の荷重／移相量分布に基づき素子アレイの指向性パターン及び所定の仕様に対するその誤差を算出するシミュレーションを実行する。ここでいう第２の荷重／移相量分布とは、第１の荷重／移相量分布に微少修正を施すことで得られる荷重／移相量分布であり、第１の荷重／移相量分布とは、初期設定された荷重／移相量分布又は前回のシミュレーションの結果として得られた荷重／移相量分布である。
【０００８】
第２のステップでは、第２の荷重／移相量分布に基づき算出した誤差が第１の荷重／移相量分布に基づき算出済の誤差より小さいとき、即ち微少修正を施した後の荷重／移相量分布（第２の荷重／移相量分布）を用いたほうが誤差が小さくなることが判明したときには、それまでの第２の荷重／移相量分布を新たな第１の荷重／移相量分布として用いることにする。逆に、第２の荷重／移相量分布に基づき算出した誤差が第１の荷重／移相量分布に基づき算出した誤差より大きいとき、即ち微少修正を施した後の荷重／移相量分布を用いると誤差が却って大きくなることが判明したときには、それまでの第１の荷重／移相量分布をそのまま第１の荷重／移相量分布として用い続ける。また、微少修正の対象となる素子を選択決定するに際しては、まず、誤差の変化動向に応じ荷重／移相量分布のなかから修正を施すべき部分領域を特定し、特定した部分領域に関連する一般に複数の素子の中から乱数的に、微少修正の対象となる素子を選択決定する。このように、乱数による処理を素子の決定に際して採用しているため、局所解に到達する確率が減り、最適解に到達しやすくなる。
【０００９】
更に、第３のステップでは、第１の荷重／移相量分布に基づきシミュレーションにて得られた指向性パターンが所定の仕様を満たすときに、その時点での第１の荷重／移相量分布を合成結果として出力する。逆に、仕様を満たしていないときには、上記誤差を記憶して再度シミュレーションを実行させる。従って、第１のステップにおけるシミュレーションは、（原則として）仕様を満たす指向性パターンが得られるまで繰返し実行され、そのような指向性パターンが得られたときに、当該指向性パターンに係る荷重／移相量分布が出力されることになる。
【００１０】
本発明の特徴の一つは、シミュレーションの繰返し実行に伴い指向性パターンの算出結果に現れる仕様に対する誤差、特にその変動傾向に基づき、シミュレーションに関連する各種の処理を実行していることである。例えば、シミュレーションの繰返し実行に伴い誤差に現れた変動傾向に応じ、第２のステップにて誤差の評価に用いる評価関数を自動切替することや、指向性パターンのうち微小修正の対象となる部分を自動選択することや、微少修正の対象となる素子を自動選択することや、微少修正の量を自動変化させることによって、誤差の変動傾向に関する情報をシミュレーションに反映させることができる。その結果、解に迅速に収束する方向でシミュレーションが繰り返されることになるため、荷重／移相量分布等を厳密に初期設定する必要がなくなり、設計できる指向性や収束判定条件設定の自由度が高まる。
【００１１】
また、シミュレーションの繰返し実行に伴い誤差に現れる変動傾向は、シミュレーション実行時に算出している誤差を保存及び処理することにより導出できる。具体的には、シミュレーションの際に算出される誤差からの最大値又は平均値を求め過去所定期間に亘り比較することにより、誤差の変動傾向を求める。または、記憶している誤差に基づき例えば誤差の変化率の形態で導出する。好ましくは、この変化率を、算出の基礎となる回数を変えて複数通り算出し、その結果を総合することによって、変化動向を検出する。このように、変化動向及び現状況の導出の基礎となる情報は、素子の形状・配置・単体での指向性等に直接には依存しないため、これらの設定の面での制約が緩くなる。
【００１３】
更に、誤差が微少修正に伴い減少したときには微少修正の量を増加させ、増加したときには減少させることによって、解への収束を更に迅速化できる。特に、微少修正に伴い誤差が減少したときであっても前所定回数内の微少修正の際に誤差が増加している場合には微少修正の量をそれまで通りに維持し、微少修正に伴い誤差が増加したときであっても前所定回数内の微少修正の際に誤差が減少している場合には微少修正の量をそれまで通りに維持するようにすれば、誤差の変動傾向をより強く微少傾向の量に反映させることができ、解への収束を更に迅速化できる。また、微少修正の量を利用した終了条件を付加することもできる。具体的には、シミュレーションにて得られた指向性パターンが仕様を満たすに至っていないときであっても、微少修正の量が所定値を下回るに至ったときには、シミュレーションの再度の実行を回避しその時点での第１の荷重／移相量分布を合成結果として出力するようにすればよい。
【００１４】
【発明の実施の形態】
以下、本発明の好適な実施形態に関し図面に基づき説明する。
【００１５】
まず、本発明の一実施形態に係る方法は、図１に示すように素子単体指向性計算部１４及び指向性合成処理部１６を備えるコンピュータ等を用いて実現することができる。素子単体指向性計算部１４は、各素子の形状や構造を示す素子形状データ、例えば素子形状・構造の種類と対応付けられている識別符号（ＩＤ）が設計作業者から与えられると、このデータに従い、素子単体での指向性を示す素子単体指向性データを発生させる。素子単体指向性データは、三次元空間内での指向性を表現できるよう角度情報及び利得情報から構成されており、指向性合成処理部１６に供給される。
【００１６】
指向性合成処理部１６には、更に、設計作業者から、三次元空間内での各素子の位置・相対的位置関係を示す素子配列データ、実現すべき指向性パターンに関する仕様を与える指向性パターンデータ、及びシミュレーションの繰返しのため初期的に与える荷重／移相量分布である荷重／移相量初期値データが、入力される。指向性合成処理部１６は、図２に示すように、これら素子単体指向性データ、素子配列データ、指向性パターンデータ及び荷重／移相量初期値データを入力し（１００）、所定の終了条件が成立するまでシミュレーションを繰返し実行し（１２４，１２６）、その結果得られた荷重／移相量初期値データを設計の結果として出力する。
【００１７】
図２においては、荷重／移相量分布に微少変更を施し、その荷重／移相量分布と素子単体指向性データ及び素子配列データとに基づき、素子アレイの指向性パターン及びこの指向性パターンが上述の仕様に対して有している誤差を算出するというシミュレーションを（１１４）、繰返し実行している。ここで算出されている誤差は、今回の微少修正を採用するか否かを判定するために使用される（１１６）。即ち、ステップ１１６では、微少変更前の荷重／移相量分布に基づき算出された指向性パターンの誤差と、微少変更後の荷重／移相量分布に基づき算出された指向性パターンの誤差とを比較する。前者よりも後者の方が小さければ、微少変更の採用によって仕様に対する誤差を低減できるため、次にステップ１１４を実行する際に“微少変更前の荷重／移相量分布”として用いるべく、微少変更を採用する（１１８）。そうでなければ微少変更は採用せず、今回“微少変更前の荷重／移相量分布”として用いた荷重／移相量分布を引き続き“微少変更前の荷重／移相量分布”として用いることとする。
【００１８】
ステップ１１４で算出した誤差は記憶しておき、次回ステップ１１４を実行する際に“微少変更前の荷重／移相量分布に基づき算出された指向性パターンの誤差”として用いる。更に、ステップ１１４及び１１６を実行するには、上記微少修正に際しどの素子の荷重・移相量を修正するのか、微少修正の量をどの程度とするのか、どのような手法で誤差を評価するのか、等を予め与えておかねばならない。本実施形態では、指向性パターンの算出結果に現れている誤差がシミュレーションの繰返しに伴いどのように変化しているのかを示す情報を、記憶している誤差に基づき導出し、その結果に基づき、微少修正の対象等をシミュレーションの繰返しの経過で適宜変更設定している。
【００１９】
まず、微少修正の対象となる素子を決定する際には、指向性合成処理部１６は、荷重に関し規格化を施した上で（１０２）、過去の誤差変化率を３通り計算する（１０４）。即ち、ステップ１１４に係るシミュレーションを繰り返したことに伴い誤差が長期的、中期的及び短期的にみてどの程度変化しているかを、記憶している誤差に基づいて算出する。指向性合成処理部１６は、ステップ１０４にて算出した誤差変化率に基づいて、ステップ１１６にて算出された指向性パターンのどの部分を微少修正に供すればよいかを判別決定し（１０６）、更にその部分に関連する１個又は複数個の素子の中から１個又は複数個の素子を自動的かつ乱数的に選び、その素子に係る荷重／移相量を微少修正の対象とする（１０８）。また、指向性合成処理部１６は、指向性パターンのどの部分を微少修正に供することとしたか又はどの素子を微少修正に供することとしたかを示す情報を、後にステップ１０６及び１０８を実行する際使用すべく、記憶する。即ち、これまでに指向性パターン中の微少修正に供しようとした箇所や微少修正に係る素子と、計算した誤差変化率とを照合することで、今回微少修正に供すべき箇所や素子を決定する。更に、局所解への収束を避けるべく、指向性合成処理部１６は、素子を選択するに際して上述のように乱数を用いている。
【００２０】
指向性合成処理部１６は、次に、記憶している過去の誤差から、各回のシミュレーションについての誤差の最大値及び平均値を算出し（１１０）、最近所定回数分のシミュレーションにおいてこれら最大値及び平均値がどのように変化しているかに応じ、最大値関数及び平均値関数のなかから一つを選んで、ステップ１０６で選択された部分の誤差を評価するための評価関数とする（１１２）。ここで選択した評価関数は、ステップ１１６にて誤差の大小を評価するために使用する関数である。従って、本実施形態では、微少修正の対象たる素子のみならず、誤差の評価にも、過去における誤差の変化動向が反映されることとなる。
【００２１】
更に、ステップ１１６及び１１８に続いて実行されるステップ１２０では、指向性合成処理部１６は、ステップ１１８の実行履歴に基づき、荷重／移相量分布の修正量を変更する。即ち、最近のシミュレーションで所定回数以上連続してステップ１１８が実行されたときには修正量を増加させ、最近のシミュレーションで所定回数以上連続してステップ１１８が実行されなかったときには減少させる。従って、本実施形態では、ステップ１１８の実行履歴を通じ、過去における誤差の変化動向を修正量に反映させることができる。
【００２２】
指向性合成処理部１６は、更に、記憶されている誤差に基づき今回のシミュレーションにおける最大誤差を計算し（１２２）、計算した最大誤差が所定値を下回るときや（１２４）、修正量が所定の微少値εを下回ったときに（１２６）、シミュレーションの繰返しを終了する。なお、図２に示した手順に、四則演算、対数演算、論理演算等を用いた制約条件を加味することもできる。
【００２３】
図３及び図４に、本実施形態に係る方法を用いて設計を行った例を示す。まず、図３に“本方式”として示した指向性パターンは、素子形状データとして波長の１／２に相当する寸法を有する矩形素子を示すデータを、素子配列データとして波長の１／２に相当する間隔にて素子を直線状に２０個配列したことを示すデータを、更に指向性パターンデータとして−９０度〜−１０度方向では−３４ｄＢ以下、０度〜２０度方向では０〜−３ｄＢ、３０度〜７０度方向では−２０〜−２３ｄＢという仕様を示すデータを、それぞれ与えた場合に、シミュレーションの繰返しにより最終的に得られた荷重／移相量分布による指向性パターンである。比較のため破線で示した従来の線形計画法と比較すると、より仕様に近い指向性パターンが得られていることがわかる。また、図４は、「準理想ビーム送受波器の最適設計」（笹倉他、海洋音響学会誌１７巻第２号）の開示に従い各データを与えた例であり、当該論文に記載されている特性に近い特性が得られていることがわかる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る装置の構成を示すブロック図である。
【図２】この実施形態における指向性合成処理部の動作の流れを示すフローチャートである。
【図３】合成例を示す図である。
【図４】合成例を示す図である。
【図５】超音波振動子アレイの概略構成を示すブロック図である。
【符号の説明】
１４素子単体指向性計算部、１６指向性合成処理部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a directivity synthesis processing method for determining a load / phase shift amount distribution in an element array such as an ultrasonic transducer array and an array antenna so as to match a desired directivity pattern (specification).
[0002]
[Prior art and its problems]
As shown in FIG. 5, the ultrasonic transducer array has a configuration in which a plurality of transducers 10 are spatially distributed and connected to each other by a coupling / distribution unit 12. When transmitting an ultrasonic signal from this array, an electrical signal is input to the coupling / distribution unit 12 from a transmitter (not shown). The coupling / distribution unit 12 distributes this signal to each transducer 10 according to the weight (load) given to each transducer 10, and further shifts the phase according to the phase shift amount given to each transducer 10. Let Each transducer 10 converts the supplied electrical signal into an ultrasonic signal. On the contrary, when an ultrasonic signal is received by this array, the received ultrasonic signal is converted into an electric signal by each transducer 10 and supplied to the coupling / distribution unit 12. The coupling / distribution unit 12 shifts the phase of the signal according to the phase shift amount described above, and further couples (weights and adds) the signal according to the load described above and supplies it to a receiver not shown. Here, the phase shift function is a partial function of the coupling / distribution unit 12, but this is for simplification of description.
[0003]
Since each transducer 10 has a specific directivity determined by its structure and the like, the load / phase shift amount, that is, ultrasonic vibration, associated with each transducer 10 is given after the spatial arrangement of the transducer 10 is given. By determining the load / phase shift distribution in the child array, the directivity pattern of the ultrasonic transducer array can be determined. Therefore, the load / phase shift amount distribution based on the directivity of each vibrator 10 alone, the spatial arrangement of each vibrator 10, the directivity pattern (specification) to be realized, and the initial value of the load / phase shift distribution. The ultrasonic transducer array having a directional pattern that satisfies the specifications can be designed. The present invention also relates to an array antenna having a configuration in which a plurality of antenna elements are spatially distributed and coupled by a coupler / distributor. For example, “directivity synthesis of a waveguide slot array antenna by linear programming” (Hara et al., Electronics As disclosed in the Journal of Communication Association of Japan, July 1983, Vol. J66-B, No. 7) and the like, a method for performing the design using linear programming is known. Since this method can be implemented by computer simulation, it is useful for automating the work of designing devices such as ultrasonic transducer arrays and array antennas (collectively referred to as “element arrays” in this application).
[0004]
However, this method has a problem in that it generally lacks flexibility. First, the design method described above can be used only for element arrays that satisfy the predetermined conditions in terms of the shape, arrangement, and directivity of each element (ultrasonic transducer, antenna element, etc.). ing. Furthermore, there is a limit to the specification that can be given (directivity pattern that can be designed), and the design operator cannot give the desired specification. Furthermore, a condition (convergence determination condition) for detecting that the load / phase shift amount distribution has converged to the solution has to be strictly set, and there is a difficulty in changing the convergence determination condition. In addition, it is difficult to appropriately insert a constraint condition regarding processing into the simulation process. In addition, the solution may change depending on the initial setting contents such as the load / phase shift amount distribution, and the local solution may be reached instead of the optimal solution.
[0005]
SUMMARY OF THE INVENTION
One of the objects of the present invention is to provide a method with a low degree of freedom or a high degree of freedom in terms of element shape, arrangement, directivity of a single element, directivity that can be designed, convergence judgment conditions, constraint conditions, and the like. is there. One of the objects of the present invention is to provide a technique that does not require a strict initial setting, is easy to use, and easily reaches an optimal solution.
[0006]
In the directivity synthesis processing method according to the present invention, the first step of executing the simulation related to the directivity pattern, the second step of determining whether or not the fine correction is possible and executing the fine correction, and the repeated execution of the simulation are finished. It is premised on the third step of determining whether or not.
[0007]
Among these steps, in the first step, a simulation for calculating the directivity pattern of the element array and its error with respect to a predetermined specification is executed based on the second load / phase shift amount distribution. Here, the second load / phase shift amount distribution is a load / phase shift amount distribution obtained by making a slight modification to the first load / phase shift amount distribution, and the first load / phase shift amount. The distribution is an initially set load / phase shift amount distribution or a load / phase shift amount distribution obtained as a result of the previous simulation.
[0008]
In the second step, when the error calculated based on the second load / phase shift amount distribution is smaller than the error calculated based on the first load / phase shift amount distribution, that is, the load / When it is found that using the phase shift amount distribution (second load / phase shift amount distribution) reduces the error, the previous second load / phase shift amount distribution is replaced with the new first load / phase shift distribution. It will be used as a phase distribution. On the contrary, when the error calculated based on the second load / phase shift amount distribution is larger than the error calculated based on the first load / phase shift amount distribution, that is, the load / phase shift amount distribution after performing a slight correction. When it is found that the error becomes larger when using, the first load / phase shift amount distribution up to that point is used as it is as the first load / phase shift amount distribution. Further, when selecting and determining an element to be subjected to a minute correction, first, a partial area to be corrected is specified from the load / phase shift distribution according to a change trend of an error, and the element is related to the specified partial area. In general, an element to be subjected to minute correction is selected and determined randomly from a plurality of elements. As described above, since the process using random numbers is adopted in determining the elements, the probability of reaching the local solution is reduced, and the optimal solution is easily reached.
[0009]
Further, in the third step, when the directivity pattern obtained by the simulation based on the first load / phase shift amount distribution satisfies a predetermined specification, the first load / phase shift amount distribution at that time point Is output as a composite result. Conversely, when the specification is not satisfied, the error is stored and the simulation is executed again. Therefore, the simulation in the first step is repeatedly executed (in principle) until a directivity pattern satisfying the specification is obtained, and when such a directivity pattern is obtained, the load / transfer related to the directivity pattern is obtained. The phase distribution is output.
[0010]
One of the features of the present invention is that various processes related to the simulation are executed based on an error with respect to the specification that appears in the calculation result of the directivity pattern, particularly its variation tendency, as the simulation is repeatedly executed. For example, the evaluation function used for error evaluation in the second step is automatically switched according to the variation tendency that appears in the error due to the repeated execution of the simulation, or the portion of the directivity pattern that is subject to minute correction is selected. Information relating to error fluctuation trends can be reflected in the simulation by automatically selecting, automatically selecting an element to be subjected to minute correction, or by automatically changing the amount of minute correction. As a result, since the simulation is repeated in a direction that converges quickly to the solution, there is no need to strictly initialize the load / phase shift amount distribution, etc., and the design directivity and the degree of freedom for setting the convergence judgment condition are increased. Rise.
[0011]
In addition, the fluctuation tendency that appears in the error as the simulation is repeatedly executed can be derived by storing and processing the error calculated at the time of executing the simulation. Specifically, the error fluctuation tendency is obtained by obtaining the maximum value or the average value from the error calculated during the simulation and comparing the obtained values over the past predetermined period. Alternatively, it is derived based on the stored error, for example, in the form of an error change rate. Preferably, this change rate is calculated in a plurality of ways by changing the number of times as a basis of calculation, and the change trend is detected by integrating the results. As described above, the information that is the basis for the derivation of the change trend and the current situation does not depend directly on the shape, arrangement, directivity, etc. of the element, so that restrictions on these settings are relaxed.
[0013]
Furthermore, by increasing the amount of minor correction when the error decreases with minor correction, and decreasing it when it increases, convergence to the solution can be further accelerated. In particular, even if the error has decreased due to the minor correction, if the error has increased during the minor correction within the previous predetermined number of times, the amount of the minor correction is maintained as it is, and the minor correction Even if the error has increased, if the error has decreased during the minor correction within the previous predetermined number of times, if the amount of the minor correction is maintained as it is, the fluctuation tendency of the error can be further increased. It can be strongly reflected in the amount of minute tendency, and the convergence to the solution can be further accelerated. In addition, an end condition using the amount of minute correction can be added. Specifically, even if the directivity pattern obtained in the simulation does not meet the specifications, if the amount of fine correction falls below a predetermined value, the simulation is not executed again. The first load / phase shift amount distribution at the time may be output as a synthesis result.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0015]
First, the method according to an embodiment of the present invention can be realized by using a computer or the like including the element single directivity calculation unit 14 and the directivity synthesis processing unit 16 as shown in FIG. The element unit directivity calculation unit 14 receives element shape data indicating the shape and structure of each element, for example, when an identification code (ID) associated with the element shape / structure type is given from the design operator. In accordance with the above, element directivity data indicating the directivity of the element alone is generated. The element simplex directivity data is composed of angle information and gain information so that directivity in the three-dimensional space can be expressed, and is supplied to the directivity synthesis processing unit 16.
[0016]
Further, the directivity synthesis processing unit 16 provides the element arrangement data indicating the position / relative positional relationship of each element in the three-dimensional space from the design operator, and the directivity pattern that gives specifications regarding the directivity pattern to be realized. Data and load / phase shift amount initial value data, which is a load / phase shift amount distribution initially given for the repetition of the simulation, are input. As shown in FIG. 2, the directivity synthesis processing unit 16 inputs the single element directivity data, the element array data, the directivity pattern data, and the load / phase shift amount initial value data (100), and a predetermined end condition. The simulation is repeatedly executed until the condition is satisfied (124, 126), and the load / phase shift amount initial value data obtained as a result is output as a design result.
[0017]
In FIG. 2, the load / phase shift amount distribution is slightly changed, and the directivity pattern of the element array and the directivity pattern are determined based on the load / phase shift amount distribution, the single element directivity data, and the element array data. A simulation (114) of repeatedly calculating an error for the above specifications is repeatedly executed. The error calculated here is used to determine whether or not to adopt the current minute correction (116). That is, in step 116, an error of the directivity pattern calculated based on the load / phase shift amount distribution before the minute change and an error of the directivity pattern calculated based on the load / phase shift amount distribution after the minute change are obtained. Compare. If the latter is smaller than the former, it is possible to reduce the error with respect to the specification by adopting a minute change. Therefore, when executing the next step 114, a slight change is made to use as "load / phase shift amount distribution before the minute change" Is adopted (118). Otherwise, the minute change is not adopted and the load / phase shift distribution used as the “load / phase shift distribution before the minor change” is used as the “load / phase shift distribution before the minor change”. And
[0018]
The error calculated in step 114 is stored and used as the “directivity pattern error calculated based on the load / phase shift amount distribution before slight change” when step 114 is executed next time. Further, in order to execute steps 114 and 116, which element load / phase shift amount is corrected in the above-described minute correction, how much is the amount of the minute correction, and what method is used to evaluate the error? , Etc. must be given in advance. In the present embodiment, information indicating how the error appearing in the calculation result of the directivity pattern changes with the repetition of the simulation is derived based on the stored error, and based on the result, The target of minute correction is appropriately changed and set as the simulation is repeated.
[0019]
First, when determining an element to be subjected to minute correction, the directivity synthesis processing unit 16 performs normalization on the load (102), and calculates three past error change rates (104). . That is, how much the error has changed in the long-term, medium-term and short-term as the simulation related to step 114 is repeated is calculated based on the stored error. The directivity synthesis processing unit 16 determines and determines which part of the directivity pattern calculated in step 116 should be subjected to the fine correction based on the error change rate calculated in step 104 (106). Further, one or a plurality of elements are automatically and randomly selected from one or a plurality of elements related to the portion, and the load / phase shift amount related to the element is subject to slight correction ( 108). Further, the directivity synthesis processing unit 16 executes steps 106 and 108 later with information indicating which part of the directivity pattern is to be subjected to the fine correction or which element is to be subjected to the fine correction. Remember to use it. That is, the location or element to be subjected to the micro correction this time is determined by collating the portion of the directivity pattern that has been used for the micro correction or the element related to the micro correction with the calculated error change rate. . Furthermore, in order to avoid convergence to a local solution, the directivity synthesis processing unit 16 uses random numbers as described above when selecting elements.
[0020]
Next, the directivity synthesis processing unit 16 calculates the maximum value and the average value of errors for each simulation from the stored past errors (110), and these maximum values and Depending on how the average value is changed, one of the maximum value function and the average value function is selected as an evaluation function for evaluating the error of the portion selected in step 106 (112). . The evaluation function selected here is a function used for evaluating the magnitude of the error in step 116. Therefore, in the present embodiment, not only the element that is the object of the minute correction but also the error evaluation reflects the past error change trend.
[0021]
Further, in step 120 executed following steps 116 and 118, the directivity synthesis processing unit 16 changes the correction amount of the load / phase shift amount distribution based on the execution history of step 118. That is, the correction amount is increased when step 118 is executed continuously for a predetermined number of times or more in the recent simulation, and is decreased when step 118 is not executed continuously for the predetermined number of times or more in the recent simulation. Therefore, in the present embodiment, the past change trend of errors can be reflected in the correction amount through the execution history of step 118.
[0022]
The directivity synthesis processing unit 16 further calculates the maximum error in this simulation based on the stored error (122), and when the calculated maximum error falls below a predetermined value (124), the correction amount is a predetermined amount. When the value is smaller than the minute value ε (126), the simulation is terminated. Note that a constraint condition using four arithmetic operations, logarithmic operations, logical operations, etc. can be added to the procedure shown in FIG.
[0023]
3 and 4 show an example of designing using the method according to the present embodiment. First, the directivity pattern shown as “this method” in FIG. 3 corresponds to data indicating a rectangular element having a dimension corresponding to ½ of the wavelength as element shape data, and corresponding to ½ of the wavelength as element arrangement data. The data indicating that 20 elements are arranged in a straight line at the intervals to be further divided into directivity pattern data of -34 dB or less in the -90 degree to -10 degree direction, 0 to -3 dB in the 0 degree to 20 degree direction, In the direction of 30 degrees to 70 degrees, when data indicating a specification of -20 to -23 dB is given, it is a directivity pattern based on the load / phase shift amount distribution finally obtained by repeating the simulation. Compared with the conventional linear programming method indicated by a broken line for comparison, it can be seen that a directivity pattern closer to the specification is obtained. FIG. 4 is an example in which each data is given in accordance with the disclosure of “Optimum design of quasi-ideal beam transducer” (Sakura et al., Journal of Ocean Acoustics, Vol. 17, No. 2), and is described in the paper. It turns out that the characteristic close | similar to the characteristic is acquired.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an operation flow of a directivity synthesis processing unit in this embodiment.
FIG. 3 is a diagram illustrating a synthesis example.
FIG. 4 is a diagram illustrating a synthesis example.
FIG. 5 is a block diagram showing a schematic configuration of an ultrasonic transducer array.
[Explanation of symbols]
14 element unit directivity calculation unit, 16 directivity synthesis processing unit.

Claims

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
According to the fluctuation tendency appearing in the error as the simulation is repeatedly executed, the element to be subject to the minute correction is automatically selected, and further, correction is made from the load / phase shift amount distribution according to the change trend. A directivity synthesis processing method characterized by specifying a partial area to be selected, and selecting and determining an element to be subjected to the above-mentioned fine correction in a random manner from a plurality of elements generally related to the specified partial area.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
The evaluation function used for the evaluation of the error in the second step is automatically switched in accordance with the fluctuation tendency appearing in the error accompanying the repeated execution of the simulation, and the fluctuation appearing in the error accompanying the repeated execution of the simulation. Depending on the trend, the elements to be subject to the above-mentioned minute correction are automatically selected, and further, the partial area to be corrected is specified from the load / phase shift distribution according to the change trend, and the related partial area is related. In general, a directivity synthesis processing method characterized by selecting and determining an element to be subjected to the fine correction from a plurality of elements in a random manner.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
According to the fluctuation trend that appears in the error due to the repeated execution of the simulation, the portion related to the minute correction is automatically selected from the directivity pattern, and according to the fluctuation tendency that appears in the error due to the repeated execution of the simulation. In addition, the elements to be subject to the minute correction are automatically selected, and the partial area to be corrected is specified from the load / phase shift distribution according to the change trend. Randomly select from the above elements A directivity synthesis processing method characterized by selecting and determining a positive target element.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. When the error is smaller than the calculated error based on the load / phase shift amount distribution of 1, the second load / phase shift amount distribution is determined. Otherwise, the first load / phase shift amount distribution is changed to the first load / phase shift amount distribution. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
The evaluation function used for the evaluation of the error in the second step is automatically switched according to the fluctuation tendency appearing in the error with the repeated execution of the simulation, and the maximum error calculated in the simulation is further changed. A directivity synthesis processing method characterized in that the fluctuation tendency is derived by obtaining a value or an average value and comparing the obtained maximum value or average value over a past predetermined period.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
According to the fluctuation tendency appearing in the error due to the repeated execution of the simulation, the portion related to the fine correction is automatically selected from the directivity pattern, and the maximum value or average of the error calculated during the simulation is further selected. A directivity synthesis processing method characterized in that the fluctuation tendency is derived by obtaining a value and comparing the obtained maximum value or average value over a predetermined period in the past.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
According to the fluctuation tendency that appears in the error with the repeated execution of the simulation, the element to be subject to the fine correction is automatically selected, and further, the maximum value or average value of the error calculated in the simulation is obtained, A directivity synthesis processing method, wherein the fluctuation tendency is derived by comparing the obtained maximum value or average value over a predetermined period in the past.

Regarding the second load / phase shift amount distribution obtained by performing a slight correction on the first load / phase shift amount distribution which is initially set or obtained in the previous simulation, the second A first step of executing a simulation for calculating the directivity pattern of the element array based on the load / phase shift amount distribution and the error with respect to a predetermined specification, and the error calculated based on the second load / phase shift amount distribution The second load / phase shift amount distribution is smaller when the calculated error is smaller than the error calculated based on the first load / phase shift amount distribution, and the first load / phase shift amount distribution is otherwise determined. When the directivity pattern obtained by the simulation based on the second step of setting the load / phase shift amount distribution of 1 and the simulation based on the first load / phase shift amount distribution satisfies a predetermined specification, And a third step of outputting the first load / phase shift amount distribution as a synthesis result, and otherwise storing the error and executing the simulation again. Oite,
By automatically switching the evaluation function used for the evaluation of the error in the second step in accordance with the variation tendency appearing in the error with the repeated execution of the simulation, and further calculating the rate of change of the error, A directivity synthesis processing method characterized by deriving the change trend.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
According to the variation tendency appearing in the error due to the repeated execution of the simulation, the change trend is calculated by automatically selecting the portion related to the minute correction in the directivity pattern and calculating the change rate of the error. A directivity synthesis processing method characterized by deriving.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
Deriving the trend of change by automatically selecting the element to be subjected to the fine correction according to the variation tendency appearing in the error as the simulation is repeatedly executed, and further calculating the rate of change of the error. A directivity synthesis processing method characterized by the above.

The directivity synthesis processing method according to any one of claims 1 to 9 ,
A directivity synthesis processing method, wherein the amount of the minute correction is automatically changed according to a variation tendency appearing in the error as the simulation is repeatedly executed.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. From the calculated error based on the load / phase shift distribution of 1 A second step of setting the second load / phase shift amount distribution as the first load / phase shift amount distribution when the second load / phase shift amount distribution is small, and the first load / phase shift amount distribution as the first load / phase shift amount distribution; When the directivity pattern obtained in the simulation based on the load / phase shift amount distribution satisfies a predetermined specification, the first load / phase shift amount distribution at that time is output as a synthesis result. A third step of storing the error and executing the simulation again.
The amount of the minute correction is automatically changed according to the fluctuation tendency appearing in the error as the simulation is repeatedly executed, and when the error is reduced with the minute correction, the amount of the minute correction is increased. Even if the error is reduced due to the fine correction, if the error has increased during the fine correction within the previous predetermined number of times, the amount of the fine correction is maintained as it is. Furthermore, even when the error increases with the fine correction, if the error is reduced during the fine correction within the predetermined number of times before, the amount of the fine correction is maintained as it is. A directivity synthesis processing method characterized by the above.

Regarding the second load / phase shift amount distribution obtained by making a slight correction to the first load / phase shift amount distribution that is initially set or obtained in the previous simulation, the second load / phase shift amount The first step of executing a simulation for calculating the directivity pattern of the element array based on the quantity distribution and its error with respect to a predetermined specification, and the error calculated based on the second load / phase shift quantity distribution are the first ones. The second load / phase shift amount distribution is smaller than the calculated error based on the load / phase shift amount distribution of 1, and the first load / phase shift amount distribution is different from the first load / phase shift distribution otherwise. When the directivity pattern obtained by the simulation based on the second step of setting the phase amount distribution and the first load / phase shift amount distribution satisfies a predetermined specification, the first load at that time / Phase shift amount In the output as synthesized result, directivity synthesis processing method having a third step of executing the simulation again stores the error otherwise,
The amount of the minute correction is automatically changed according to the variation tendency appearing in the error as the simulation is repeatedly executed, and the directivity pattern obtained in the simulation does not satisfy the specifications. However, when the amount of the minute correction falls below a predetermined value, the second execution of the simulation is avoided and the first load / phase shift amount distribution at that time is output as a synthesis result. Directivity synthesis processing method.