JP7352948B2 - Airspeed and wind direction measuring device for aircraft and its measurement method - Google Patents
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Description
本発明は、飛行体、特に低速で飛行する小型ＵＡＶ（Unmanned Aerial Vehicle）に搭載する対気速度及び風向計測装置及びその計測方法に関するものである。 The present invention relates to an airspeed and wind direction measuring device mounted on an aircraft, particularly a small UAV (Unmanned Aerial Vehicle) flying at low speed, and a measuring method thereof.
特許文献１（特許第３５７４８１４号公報）に記載されるように、航空機の前方方向に向けその軸芯が三角形の各頂点に位置するように機体に取り付けられた３本の平行な支持棒上に、複数個の超音波送受信機を軸方向に位置を異ならせて配備し、隣接する支持棒上の超音波送受信機との組合せで複数組の超音波送受信経路が形成されるようにし、所定距離の前記複数組の超音波送受信経路を伝搬する時間情報から対気速度に関する三次元情報を得るものが提案されている。 As described in Patent Document 1 (Japanese Patent No. 3574814), three parallel support rods are attached to the aircraft so that their axes are located at each vertex of a triangle toward the front of the aircraft. , a plurality of ultrasonic transceivers are arranged at different positions in the axial direction, and in combination with ultrasonic transceivers on adjacent support rods, multiple sets of ultrasonic transceiver paths are formed, and It has been proposed to obtain three-dimensional information regarding airspeed from time information propagating through the plurality of sets of ultrasonic transmission and reception paths.
また、特許文献２（特許第６３４７４６９号公報）には、無人航空機の回転翼よりも高い位置に風向及び風速を計測する気象観測部を配置する点（特に、段落００１９～００２１及び図１を参照）や、気象観測部を構成する風向風速計測器がアンテナａ、アンテナｂ及びアンテナｃを等間隔に配置したものであり、超音波（２０ｋＨｚ以上の周波数の信号）を利用してアンテナａ－アンテナｂ間、アンテナｂ－アンテナｃ間及びアンテナｃ－アンテナａ間の３方向の風のベクトルを同時に算出して、正確な風向と風速を測定する点（特に、段落００２８～００３１及び図３を参照）が記載されている。 Furthermore, in Patent Document 2 (Patent No. 6347469), a meteorological observation unit for measuring wind direction and wind speed is arranged at a higher position than the rotor of the unmanned aircraft (see especially paragraphs 0019 to 0021 and FIG. 1). ), and the wind speed and direction measuring instruments that make up the weather observation section have antennas a, b, and c arranged at equal intervals, and use ultrasonic waves (signals with a frequency of 20 kHz or higher) to connect antenna a to antenna. The point is that the wind vectors in three directions are calculated simultaneously between antenna b and antenna c, and between antenna c and antenna a to measure accurate wind direction and wind speed (in particular, see paragraphs 0028 to 0031 and Figure 3). ) are listed.
一般的に、小型ＵＡＶは低速で飛行するため、その対気速度の計測が困難である。
通常、航空機の対気速度の計測にはピトー管流速計が使われているが、ピトー管流速計では、対気速度が４ｍ／秒の場合、差圧が１ｍｍＨ2Ｏしか発生せず、低速領域の計測に対しては、傾斜マノメータや高感度の圧力変換器が必要となる。
そのため、小型化や軽量化が難しい上に、コストがかさむという問題があり、また、応答性が悪いため、対気速度の変動を計測できないという問題もある。
特許文献１では、超音波風速計のセンサプローブを改良して、ピトー管流速計で計測できない低速領域の計測が可能である航空機用の対気速度計測装置を提供している。
また、特許文献２でも、超音波を利用して３方向の風のベクトルを同時に算出して、正確な風向と風速を測定できる風向風速計測器を提案している。
Generally, small UAVs fly at low speeds, making it difficult to measure their airspeed.
Normally, a pitot tube current meter is used to measure the airspeed of an aircraft, but with a pitot tube current meter, when the airspeed is 4 m/s, a differential pressure of only 1 mmH 2 O is generated, and at low speed For area measurements, a tilting manometer or a sensitive pressure transducer is required.
Therefore, it is difficult to reduce the size and weight of the device, and it is also expensive.Furthermore, due to poor responsiveness, it is not possible to measure airspeed fluctuations.
Patent Document 1 provides an airspeed measurement device for aircraft that improves the sensor probe of an ultrasonic anemometer and is capable of measuring low speed regions that cannot be measured with a pitot tube current meter.
Moreover, Patent Document 2 also proposes a wind direction and wind speed measuring instrument that can simultaneously calculate wind vectors in three directions using ultrasonic waves and measure accurate wind direction and wind speed.
特許文献１及び２で利用している超音波風速計の計測手法は、超音波の伝播時間差を利用する時間差法である。
すなわち、図１に示すように、２つの超音波送受信器を距離Ｌ（ｍ）だけ離して設置した１対の超音波送受信器において、２つの超音波送受信器間における風速がＶ（ｍ／秒）であれば、音速をＶｓ（ｍ／秒）とした時、空気の流れ方向に超音波が伝播する時の伝播速度はＶｓ＋Ｖとなり、空気の流れの逆方向に超音波が伝播する時の伝播速度がＶｓ－Ｖとなる。そのため、空気の流れ方向に超音波が伝播する時の伝播時間に対して、空気の流れの逆方向に超音波が伝播する時の伝播時間は長くなる。そして、一方の超音波送受信器から超音波を送信し他方の超音波送受信器でその超音波を受信するまでの伝播時間をｔ1（秒）とし、他方の超音波送受信器から超音波を送信し一方の超音波送受信器でその超音波を受信するまでの伝播時間をｔ2（秒）とすると、その伝播時間差を利用して計測される風速Ｖｔ（ｍ／秒）は、Ｖｓ＞＞Ｖｔであれば、伝播時間ｔ1を測定するために超音波を送受信した時の伝播方向を正として、下記の式（１）で表される。
Ｖｔ＝Ｖｓ2（ｔ2－ｔ1）／２Ｌ・・・・式（１）
なお、この超音波風速計を航空機に搭載すると、計測値の大きさは、風速と対地速度の和である対気速度となり、計測値の向きは対気速度と逆向きとなる。
The measurement method of the ultrasonic anemometer used in Patent Documents 1 and 2 is a time difference method that uses the difference in propagation time of ultrasonic waves.
That is, as shown in Fig. 1, in a pair of ultrasonic transceivers installed a distance L (m) apart, the wind speed between the two ultrasonic transceivers is V (m/sec). ), then when the sound speed is Vs (m/sec), the propagation speed when the ultrasonic wave propagates in the direction of the air flow is Vs + V, and the propagation speed when the ultrasonic wave propagates in the opposite direction of the air flow. The speed becomes Vs-V. Therefore, the propagation time when the ultrasonic waves propagate in the opposite direction of the air flow is longer than the propagation time when the ultrasonic waves propagate in the direction of the air flow. Then, the propagation time from when an ultrasound is transmitted from one ultrasound transceiver to when it is received by the other ultrasound transceiver is t 1 (seconds), and the ultrasound is transmitted from the other ultrasound transceiver. However, if the propagation time until one ultrasonic transmitter/receiver receives the ultrasonic wave is t 2 (seconds), then the wind speed Vt (m/second) measured using the propagation time difference is Vs >> Vt If so, it is expressed by the following equation (1), assuming that the propagation direction when transmitting and receiving ultrasonic waves to measure the propagation time t 1 is positive.
Vt=Vs 2 (t 2 - t 1 )/2L...Formula (1)
Note that when this ultrasonic anemometer is mounted on an aircraft, the magnitude of the measured value becomes the airspeed, which is the sum of the wind speed and the ground speed, and the direction of the measured value is opposite to the airspeed.
超音波の伝播時間は、例えば、図２に示すように、超音波を受信して発せられる電圧信号に対して閾値を設けて、受信信号が閾値に達することで受信を検出して測定される。このため、伝播時間の分解能は受信信号の半周期分に相当するものとなる。この伝播時間を測定する手法により測定される伝播時間から算出される対気速度よりも高い分解能が要求される場合には、何回か計測した対気速度の計測値を平均することでしか、この要求を満たすことができなかった。
しかし、小型ＵＡＶの自律制御に用いる場合、自律制御の対気速度を参照した制御ループの制御周期よりも計測器のサンプリング時間の方が短くなければならず、時間差法によって対気速度を何回も計測して平均すると応答性を満足することができない。
中心周波数の高い超音波送受信器を用いて、対気速度の分解能の向上を図ることはできるが、超音波は周波数が高いほど空気によるエネルギーの損失が大きくなって振幅が減衰し、受信信号のＳ／Ｎ比が劣化する。そのため、通常、超音波風速計には中心周波数３００ｋＨｚ程度までの超音波送受信器が用いられ、これより高い中心周波数の超音波送受信器は使用されない。また、中心周波数の高い超音波送受信器は高価であるため、これを用いた計測器を搭載する場合、小型ＵＡＶを安価に製作できなくなるという問題もある。
この発明は、これらの問題を解決しようとするものであり、低速で飛行する小型ＵＡＶ等の飛行体に適する、高い分解能で対気速度及び風向を計測できる装置及び方法を安価に提供することを目的としてなされたものである。
The propagation time of ultrasonic waves is measured, for example, by setting a threshold value for the voltage signal emitted by receiving ultrasonic waves and detecting reception when the received signal reaches the threshold value, as shown in Figure 2. . Therefore, the propagation time resolution corresponds to a half period of the received signal. If a higher resolution is required than the airspeed calculated from the propagation time measured by this method of measuring propagation time, it is possible to solve the problem by averaging the airspeed measurements taken several times. This request could not be met.
However, when used for autonomous control of small UAVs, the sampling time of the measuring instrument must be shorter than the control cycle of the control loop that refers to the airspeed of the autonomous control, and the airspeed can be adjusted several times using the time difference method. If you measure and average the results, you will not be able to satisfy the responsiveness.
It is possible to improve the resolution of airspeed by using an ultrasonic transceiver with a high center frequency, but the higher the frequency of ultrasonic waves, the greater the loss of energy through the air, which attenuates the amplitude of the received signal. The S/N ratio deteriorates. Therefore, an ultrasonic transceiver with a center frequency of up to about 300 kHz is usually used in an ultrasonic anemometer, and an ultrasonic transceiver with a center frequency higher than this is not used. Furthermore, since ultrasonic transceivers with high center frequencies are expensive, there is also the problem that small UAVs cannot be manufactured at low cost when equipped with measuring instruments using them.
The present invention aims to solve these problems, and aims to provide an inexpensive device and method that can measure airspeed and wind direction with high resolution and is suitable for low-speed flying vehicles such as small UAVs. It was done for a purpose.
請求項１に係る発明の飛行体用対気速度及び風向計測装置は、
飛行体の外面に、第１の方向についての風速を計測する第１風速計測手段及び前記第１の方向とは異なる第２の方向についての風速を計測する第２風速計測手段と、
前記第１風速計測手段で計測された第１の方向についての風速及び前記第２風速計測手段で計測された第２の方向についての風速に基づいて風向を計測する風向計測手段を備え、
前記第１風速計測手段及び前記第２風速計測手段は、いずれも
１対の超音波送受信器と、
一方の超音波送受信器が超音波を送信してから他方の超音波送受信器で該超音波を受信するまでの第１伝播時間を計測する第１伝播時間計測手段と、
前記他方の超音波送受信器が超音波を送信してから前記一方の超音波送受信器で該超音波を受信するまでの第２伝播時間を計測する第２伝播時間計測手段と、
前記第１伝播時間計測手段で計測された第１伝播時間及び前記第２伝播時間計測手段で計測された第２伝播時間に基づいて時間差風速を演算する時間差風速演算手段と、
前記一方の超音波送受信器が超音波を送信した後、前記他方の超音波送受信器で受信した第１受信信号を記録する第１受信信号記録手段と、
前記他方の超音波送受信器が超音波を送信した後、前記一方の超音波送受信器で受信した第２受信信号を記録する第２受信信号記録手段と、
前記第１受信信号記録手段で記録された第１受信信号と前記第２受信信号記録手段で記録された第２受信信号との位相差を演算する位相差演算手段と、
前記時間差風速演算手段で演算された風速及び前記超音波送受信器の支持具の超音波の伝播に関するパラメータに基づいて、前記位相差演算手段で演算された位相差を修正する位相差修正手段と、
前記位相差修正手段で修正された修正位相差に基づいて位相差風速を演算する位相差風速演算手段を有していることを特徴とする。
The airspeed and wind direction measuring device for a flying vehicle of the invention according to claim 1 comprises:
A first wind speed measuring means for measuring wind speed in a first direction and a second wind speed measuring means for measuring wind speed in a second direction different from the first direction, on the outer surface of the flying object;
Wind direction measuring means for measuring the wind direction based on the wind speed in the first direction measured by the first wind speed measuring means and the wind speed in the second direction measured by the second wind speed measuring means,
The first wind speed measuring means and the second wind speed measuring means both include a pair of ultrasonic transceivers,
a first propagation time measuring means for measuring a first propagation time from when one ultrasonic transceiver transmits an ultrasonic wave until the other ultrasonic transceiver receives the ultrasonic wave;
a second propagation time measuring means for measuring a second propagation time from when the other ultrasonic transceiver transmits an ultrasonic wave until the one ultrasonic transceiver receives the ultrasonic wave;
time difference wind speed calculation means for calculating a time difference wind speed based on a first propagation time measured by the first propagation time measurement means and a second propagation time measured by the second propagation time measurement means;
a first received signal recording means for recording a first received signal received by the other ultrasonic transceiver after the one ultrasonic transceiver transmits the ultrasonic wave;
a second received signal recording means for recording a second received signal received by the one ultrasonic transceiver after the other ultrasonic transceiver transmits the ultrasonic wave;
phase difference calculating means for calculating a phase difference between a first received signal recorded by the first received signal recording means and a second received signal recorded by the second received signal recording means;
a phase difference correction means for correcting the phase difference calculated by the phase difference calculation means based on the wind speed calculated by the time difference wind speed calculation means and a parameter related to the propagation of the ultrasonic wave of the support of the ultrasonic transmitter/receiver ;
It is characterized by comprising a phase difference wind speed calculation means for calculating a phase difference wind speed based on the corrected phase difference corrected by the phase difference correction means.
請求項２に係る発明は、請求項１に記載の飛行体用対気速度及び風向計測装置において、
前記第１の方向と前記第２の方向は、同一平面内で直交していることを特徴とする。
The invention according to claim 2 is the airspeed and wind direction measuring device for an aircraft according to claim 1,
The first direction and the second direction are perpendicular to each other within the same plane.
請求項３に係る発明の飛行体用対気速度及び風向計測方法は、
飛行体の外面に設置された第１の方向についての風速を計測する第１風速計測手段及び前記第１の方向とは異なる第２の方向についての風速を計測する第２風速計測手段を用いて、前記飛行体の対気速度及び風向を計測する方法であって、
前記第１風速計測手段及び前記第２風速計測手段が、それぞれ有している１対の超音波送受信器のうちの一方の超音波送受信器が超音波を送信してから他方の超音波送受信器で該超音波を受信するまでの第１伝播時間を計測し、
前記一方の超音波送受信器が超音波を送信した後、前記他方の超音波送受信器で受信した第１受信信号を記録し、
前記他方の超音波送受信器が超音波を送信してから前記一方の超音波送受信器で該超音波を受信するまでの第２伝播時間を計測し、
前記他方の超音波送受信器が超音波を送信した後、前記一方の超音波送受信器で受信した第２受信信号を記録し、
前記第１伝播時間及び前記第２伝播時間に基づいて時間差風速を演算し、
前記第１受信信号と前記第２受信信号との位相差を演算し、
前記時間差風速及び前記超音波送受信器の支持具の超音波の伝播に関するパラメータに基づいて前記位相差を修正し、修正位相差を演算し、
前記修正位相差に基づいて位相差風速を演算し、
前記第１風速計測手段で計測された第１の位相差風速及び前記第２風速計測手段で計測された第２の位相差風速に基づいて風向を計測することを特徴とする。
The airspeed and wind direction measuring method for a flying vehicle according to the invention according to claim 3 includes:
A first wind speed measuring means installed on the outer surface of the flying object measures the wind speed in a first direction, and a second wind speed measuring means measures the wind speed in a second direction different from the first direction. , a method for measuring the airspeed and wind direction of the aircraft, the method comprising:
The first wind speed measuring means and the second wind speed measuring means each have a pair of ultrasonic transceivers, after one of the ultrasonic transceivers transmits an ultrasonic wave, the other ultrasonic transceiver transmits an ultrasonic wave. Measure the first propagation time until receiving the ultrasonic wave at
After the one ultrasonic transceiver transmits the ultrasonic wave, recording a first reception signal received by the other ultrasonic transceiver,
Measuring a second propagation time from when the other ultrasonic transceiver transmits the ultrasonic wave until the one ultrasonic transceiver receives the ultrasonic wave,
After the other ultrasonic transceiver transmits the ultrasonic wave, recording a second reception signal received by the one ultrasonic transceiver,
calculating a time difference wind speed based on the first propagation time and the second propagation time;
calculating a phase difference between the first received signal and the second received signal;
correcting the phase difference based on the time difference wind speed and parameters related to the propagation of the ultrasonic wave of the support of the ultrasonic transmitter/receiver , and calculating a corrected phase difference;
calculating a phase difference wind speed based on the corrected phase difference;
It is characterized in that the wind direction is measured based on the first phase difference wind speed measured by the first wind speed measuring means and the second phase difference wind speed measured by the second wind speed measuring means.
請求項１に係る発明の飛行体用対気速度及び風向計測装置及び請求項３に係る発明の飛行体用対気速度及び風向計測方法によれば、小型、軽量、安価な構成によって、高い分解能で対気速度及び風向を計測でき、かつ、対気速度が小さくても正確に計測可能である。
さらに、時間差風速及び超音波送受信器の支持具の超音波の伝播に関するパラメータに基づいて位相差を修正するので、超音波送受信器の支持具を伝播した超音波を受信することによる対気速度及び風向の計測誤差を除去できる。
According to the airspeed and wind direction measurement device for an aircraft of the invention according to claim 1 and the airspeed and wind direction measurement method for an aircraft of the invention according to claim 3, high resolution can be achieved with a small, lightweight, and inexpensive configuration. It is possible to measure airspeed and wind direction, and it is possible to measure accurately even if the airspeed is small.
Furthermore, since the phase difference is modified based on the time difference wind speed and the parameters related to the propagation of the ultrasonic waves in the support of the ultrasonic transceiver, the airspeed and Measurement errors in wind direction can be removed.
請求項２に係る発明の飛行体用対気速度及び風向計測装置によれば、請求項１に係る発明の効果に加え、計測される風速の方向が同一平面内で直交しているので、風速及び風向の演算を容易に行うことができる。 According to the airspeed and wind direction measuring device for an aircraft of the invention according to claim 2, in addition to the effects of the invention according to claim 1, the directions of the measured wind speeds are orthogonal in the same plane, so that the wind speed and wind direction can be easily calculated.
図３は飛行体用対気速度及び風向計測装置の概念図である。
本発明の飛行体用対気速度及び風向計測装置は、図３に示すように、第１の方向に距離Ｌ（ｍ）の間隔で配置されている１対の超音波送受信器を有する第１風速計測手段１、第２の方向に距離Ｌ（ｍ）の間隔で配置されている１対の超音波送受信器を有する第２風速計測手段２及び第１風速計測手段１で計測された第１の方向についての位相差風速及び第２風速計測手段２で計測された第２の方向についての位相差風速に基づいて風向を計測する風向計測手段３を備えている。
なお、第１の方向及び第２の方向は同一平面内で直交している。
FIG. 3 is a conceptual diagram of an airspeed and wind direction measuring device for an aircraft.
As shown in FIG. 3, the airspeed and wind direction measuring device for an aircraft according to the present invention has a first The first wind speed measured by the wind speed measuring means 1, the second wind speed measuring means 2 having a pair of ultrasonic transceivers arranged at a distance L (m) in the second direction, and the first wind speed measuring means 1. A wind direction measuring means 3 is provided for measuring the wind direction based on the phase difference wind speed in the direction of and the phase difference wind speed in the second direction measured by the second wind speed measuring means 2.
Note that the first direction and the second direction are orthogonal within the same plane.
第１風速計測手段１は、一方の超音波送受信器４が中心周波数ｆ（Ｈｚ）の超音波を送信してから他方の超音波送受信器５でその超音波を受信するまでの第１伝播時間ｔ1（秒）を計測する第１伝播時間計測手段１１、他方の超音波送受信器５が中心周波数ｆの超音波を送信してから一方の超音波送受信器４でその超音波を受信するまでの第２伝播時間ｔ2（秒）を計測する第２伝播時間計測手段１２、第１伝播時間ｔ1及び第２伝播時間ｔ2に基づいて時間差風速Ｖ1t（ｍ／秒）を演算する時間差風速演算手段１３、一方の超音波送受信器４が超音波を送信した後、他方の超音波送受信器５で受信した第１受信信号α1を記録する第１受信信号記録手段１４、他方の超音波送受信器５が超音波を送信した後、一方の超音波送受信器４で受信した第２受信信号β1を記録する第２受信信号記録手段１５、第１受信信号α1と第２受信信号β1との位相差φ１（ｒａｄ）を演算する位相差演算手段１６、時間差風速演算手段１３で演算された風速に基づいて位相差φ１を修正する位相差修正手段１７及び位相差修正手段で修正された修正位相差φ1a（ｒａｄ）に基づいて位相差風速Ｖ1p（ｍ／秒）を演算する位相差風速演算手段１８を有している。
同様に第２風速計測手段２は、一方の超音波送受信器６が中心周波数ｆの超音波を送信してから他方の超音波送受信器７でその超音波を受信するまでの第１伝播時間ｔ3（秒）を計測する第１伝播時間計測手段２１、他方の超音波送受信器７が中心周波数ｆの超音波を送信してから一方の超音波送受信器６でその超音波を受信するまでの第２伝播時間ｔ4（秒）を計測する第２伝播時間計測手段２２、第１伝播時間ｔ3及び第２伝播時間ｔ4に基づいて時間差風速Ｖ2t（ｍ／秒）を演算する時間差風速演算手段２３、一方の超音波送受信器６が超音波を送信した後、他方の超音波送受信器７で受信した第１受信信号α2を記録する第１受信信号記録手段２４、他方の超音波送受信器７が超音波を送信した後、一方の超音波送受信器６で受信した第２受信信号β2を記録する第２受信信号記録手段２５、第１受信信号α2と第２受信信号β2との位相差φ２（ｒａｄ）を演算する位相差演算手段２６、時間差風速演算手段２３で演算された風速に基づいて位相差φ２を修正する位相差修正手段２７及び位相差修正手段で修正された修正位相差φ2a（ｒａｄ）に基づいて位相差風速Ｖ2p（ｍ／秒）を演算する位相差風速演算手段２８を有している。
なお、時間差風速Ｖ1t、Ｖ2tの演算式は、下記の式（２）及び式（３）で表される。
Ｖ1t＝Ｖｓ2（ｔ2－ｔ1）／２Ｌ・・・・式（２）
Ｖ2t＝Ｖｓ2（ｔ4－ｔ3）／２Ｌ・・・・式（３）
また、位相差風速Ｖ1p、Ｖ2pは、後述するが下記の式（４）及び式（５）で表される。
Ｖ1p＝Ｖｓ2φ1a／４πｆＬ・・・・・式（４）
Ｖ2p＝Ｖｓ2φ2a／４πｆＬ・・・・・式（５）
以下、実施例によって本発明の実施形態を説明する。
The first wind speed measurement means 1 measures the first propagation time from when one ultrasonic transceiver 4 transmits an ultrasonic wave with a center frequency f (Hz) until the other ultrasonic transceiver 5 receives the ultrasonic wave. t 1 (seconds), from when the other ultrasonic transceiver 5 transmits an ultrasonic wave with a center frequency f until one ultrasonic transceiver 4 receives the ultrasonic wave. a second propagation time measuring means 12 for measuring a second propagation time t 2 (seconds) ; calculation means 13, first received signal recording means 14 for recording the first received signal α1 received by the other ultrasonic transceiver 5 after one ultrasonic transceiver 4 transmits an ultrasonic wave, and the other ultrasonic transceiver 4; After the transmitter 5 transmits the ultrasonic wave, a second received signal recording means 15 records the second received signal β1 received by one of the ultrasonic transceivers 4, and a second received signal recording means 15 records the position of the first received signal α1 and the second received signal β1. A phase difference calculation means 16 for calculating the phase difference φ1 (rad), a phase difference correction means 17 for correcting the phase difference φ1 based on the wind speed calculated by the time difference wind speed calculation means 13, and a modified phase difference corrected by the phase difference correction means. It has a phase difference wind speed calculating means 18 that calculates a phase difference wind speed V1p (m/sec) based on φ1a (rad).
Similarly, the second wind speed measuring means 2 measures the first propagation time t from when one ultrasonic transceiver 6 transmits an ultrasonic wave with a center frequency f until the other ultrasonic transceiver 7 receives the ultrasonic wave. The first propagation time measuring means 21 measures 3 (seconds), and the period from when the other ultrasonic transceiver 7 transmits an ultrasonic wave with a center frequency f until one ultrasonic transceiver 6 receives the ultrasonic wave. A second propagation time measuring means 22 that measures a second propagation time t 4 (seconds), a time difference wind speed calculation that calculates a time difference wind speed V2t (m/second) based on the first propagation time t 3 and the second propagation time t 4 means 23, a first received signal recording means 24 for recording the first received signal α2 received by the other ultrasonic transceiver 7 after one ultrasonic transceiver 6 transmits an ultrasonic wave; A second received signal recording means 25 records the second received signal β2 received by one of the ultrasonic transmitter/receivers 6 after the ultrasonic transmitter 7 transmits an ultrasound, and a phase difference between the first received signal α2 and the second received signal β2. A phase difference calculation means 26 that calculates φ2 (rad), a phase difference correction means 27 that corrects the phase difference φ2 based on the wind speed calculated by the time difference wind speed calculation means 23, and a modified phase difference φ2a corrected by the phase difference correction means. It has a phase difference wind speed calculating means 28 which calculates a phase difference wind speed V2p (m/sec) based on (rad).
The calculation formulas for the time difference wind speeds V1t and V2t are expressed by the following formulas (2) and (3).
V1t=Vs 2 (t 2 - t 1 )/2L...Equation (2)
V2t=Vs 2 (t 4 - t 3 )/2L...Equation (3)
Further, the phase difference wind speeds V1p and V2p are expressed by the following equations (4) and (5), which will be described later.
V1p=Vs 2 φ1a/4πfL...Equation (4)
V2p=Vs 2 φ2a/4πfL...Equation (5)
Embodiments of the present invention will be described below with reference to Examples.
実施例１に係る飛行体用対気速度及び風向計測装置は、図４に示すように、図３と同様、２対の超音波送受信器を小型ＵＡＶ（ドローン）の中央部上面に取り付けたものである。
そして、対気速度及び風向の計測については、従来の超音波風速計の計測手法である伝播時間差を利用したものに、超音波を受信して発せられる電圧信号の位相差、即ち受信信号の位相差を利用したものを組み合わせることによって行う。
As shown in FIG. 4, the airspeed and wind direction measuring device for an aircraft according to Example 1 has two pairs of ultrasonic transceivers attached to the upper surface of the center of a small UAV (drone), similar to FIG. 3. It is.
For measuring airspeed and wind direction, in addition to the measurement method of conventional ultrasonic anemometers that uses the propagation time difference, there is This is done by combining things that utilize phase differences.
受信信号の位相差を利用した風速の計測原理の説明図を図５に示す。
ここでは、第１の方向における風速を計測する場合について述べる。
まず、第１伝播時間ｔ1を測定するために、一方の超音波送受信器４から超音波（中心周波数ｆの正弦波であり、ｓｉｎ２πｆｔで表される）を送信した時に、他方の超音波送受信器５でその超音波を受信して得られた信号を受信信号α1（Ａ1ｓｉｎ（２πｆｔ＋φ1）で表される）とする（ただし、Ａ1は０より大きい所定値、ｔは時間（秒）、φ1は受信信号α1と正弦波との位相差）。
そして、位相差φ1は、正弦波の周期をＴ（Ｔ＝１／ｆ）とすると、受信してからｎ波分に亘って積分することにより、下記の式（６）で表される。
そうすると、φ2は式（６）のφ1をφ2に、Ａ1をＡ2に置き換えて同様に計算でき、受信信号α1、β1の位相差を利用して計測される位相差風速Ｖｐは、φ1を算出するために超音波を送受信した時の伝播方向を正として、下記の式（７）で表される。
Ｖｐ＝Ｖｓ2（φ2－φ1）／４πｆＬ・・・・・・式（７）
FIG. 5 shows an explanatory diagram of the principle of measuring wind speed using the phase difference of received signals.
Here, a case will be described in which the wind speed in the first direction is measured.
First, in order to measure the first propagation time t 1 , when an ultrasonic wave (a sine wave with a center frequency f, expressed as sin2πft) is transmitted from one ultrasonic transmitter/receiver 4, the other ultrasonic transmitter/receiver The signal obtained by receiving the ultrasonic wave with the device 5 is the received signal α1 (expressed as A 1 sin (2πft+φ 1 )) (where A 1 is a predetermined value larger than 0, and t is the time (seconds). ), φ1 is the phase difference between the received signal α1 and the sine wave).
Then, when the period of the sine wave is T (T=1/f), the phase difference φ 1 is expressed by the following equation (6) by integrating over n waves after reception.
Then, φ 2 can be calculated in the same way by replacing φ 1 with φ 2 and A 1 with A 2 in equation (6), and the phase difference wind speed Vp measured using the phase difference between the received signals α1 and β1 is , φ 1 is expressed by the following equation (7), assuming that the propagation direction when transmitting and receiving ultrasonic waves is positive.
Vp=Vs 2 (φ 2 -φ 1 )/4πfL...Equation (7)
式（７）から分かるように、位相差風速ＶｐはＶｓ、（φ2－φ1）、ｆ及びＬから求められるため、実施例１では図６に示すように、受信信号α1と受信信号β1を記録し、両者の位相差φ2－φ1を求めることにより、演算することができる。
ところで、位相差φ1は直交座標系の上記式（６）の大括弧内における上辺及び下辺の式によって決まる偏角であり、－π＜φ1＜πの範囲で逆正接を計算でき、同様に位相差φ2も－π＜φ2＜πの範囲で逆正接を計算できる。
そのため、－２π＜φ2－φ1＜２πの範囲では計算できるが、φ2－φ1＜－２π及び２π＜φ2－φ1の範囲では正しく計算することができない。
そこで、時間差法によって計測された風速Ｖｔを基準に、位相差法により算出された位相差を修正するアンラップ処理を施すことにより、時間差法によって計測される風速Ｖｔと同等の計測範囲で高い分解能の風速を応答性良く計測できる。
アンラップ処理は、図７に示すように、時間差法で計測された風速Ｖｔの計測値として最も度数の高い値に近い計測値となるように、位相差を修正して風速Ｖｐを求める処理である。
As can be seen from equation (7), the phase difference wind speed Vp is obtained from Vs, (φ 2 −φ 1 ), f, and L. Therefore, in Example 1, as shown in FIG. 6, the received signal α1 and the received signal β1 The calculation can be performed by recording and calculating the phase difference φ 2 −φ 1 between the two.
By the way, the phase difference φ 1 is the argument determined by the upper and lower equations in the square brackets of the above equation (6) in the orthogonal coordinate system, and the arctangent can be calculated in the range -π < φ 1 < π, and similarly The arctangent of the phase difference φ 2 can also be calculated in the range -π < φ 2 < π.
Therefore, calculation is possible in the range -2π<φ 2 -φ 1 <2π, but cannot be calculated correctly in the ranges φ 2 -φ 1 <-2π and 2π<φ 2 -φ 1 .
Therefore, by performing an unwrapping process that corrects the phase difference calculated by the phase difference method using the wind speed Vt measured by the time difference method as a reference, high resolution can be achieved in the same measurement range as the wind speed Vt measured by the time difference method. Wind speed can be measured with good responsiveness.
As shown in FIG. 7, the unwrapping process is a process for determining the wind speed Vp by correcting the phase difference so that the measured value is closest to the value with the highest frequency as the measured value of the wind speed Vt measured by the time difference method. .
実施例２に係る飛行体用対気速度及び風向計測装置は、図８に示すように、図３における第１の方向（以下、「ｘsen軸方向」という。）及び第２の方向（以下、「ｙsen軸方向」という。）の２対の超音波送受信器４～７に加え、第３の方向（以下、「ｚsen軸方向」という。）に１対の超音波送受信器９、１０を設け、ｚsen軸方向における風速を計測できるようにしたものである。
飛行体の対気速度の計測には三次元情報を得ることがより望ましいため、このような３軸方向のセンサ座標系を有する装置を利用する。
As shown in FIG. 8, the airspeed and wind direction measuring device for an aircraft according to Example 2 has two directions: the first direction (hereinafter referred to as "x sen axis direction") and the second direction (hereinafter referred to as , a pair of ultrasonic transceivers 4 to 7 in the 3rd direction (hereinafter referred to as the ``z sen axis direction ' '); 10 so that the wind speed in the z sen axis direction can be measured.
Since it is more desirable to obtain three-dimensional information for measuring the airspeed of an aircraft, a device having such a sensor coordinate system in three-axis directions is used.
図９は、３対の超音波送受信器を用いた対気速度の三次元情報を示す図である。通常、センサの座標系ｘsenｙsenｚsenと機体座標系ｘｙｚとは異なるため、座標変換が必要となる。図９に示すように、３対の超音波送受信器の内、２対の超音波送受信器のそれぞれの超音波の伝播経路からなる平面において、一方の超音波の伝播経路の方向をｘsen軸とし、ｘsen軸に対して右手直交系をなすようにｙsen軸を決め、ｘsen軸及びｙsen軸に対して右手直交系をなすようにｚsen軸を決めることで、センサ座標系を設定する。
また、センサ座標系をｚsen軸周りにθ1だけ回転させ、これによりできた座標系ｘ1ｙ1ｚ1をｙ1軸周りにθ2だけ回転させ、これによりできた座標系ｘ2ｙ2ｚ2をｙ2軸周りにθ3だけ回転させてできる機体座標系ｘｙｚを設定する。
そして、図８において超音波の伝播経路がｘsen軸方向の１対の超音波送受信器４，５を除く、２対の超音波送受信器６，７，９，１０の各伝播経路とｙsen軸とのなす角をθ1，θ2とする。
さらに、３対の超音波送受信器による対気速度の計測値を、それぞれｕsen，ｖsen，ｗsenとし、ｚ軸周りにｘ軸と対気速度ベクトルとのなす角をβ、ｘｙ平面と対気速度ベクトルとのなす角をαとすると、対気速度の計測値のｘ方向成分ｕ、ｙ方向成分ｖ、ｚ方向成分ｗ、対気速度の大きさの計測値Ｖsen及び風向の計測値β，αは、下記の式（８）～（１１）で表される。
β＝arctan（ｖ／ｕ）・・・・・・・・・式（１０）
α＝arctan｛ｗ／（ｕ2＋ｖ2）1/2｝・・・・式（１１）
ただし、Ｒxyz
senは機体座標系からセンサ座標系に変換する回転行列で、Ｒsenは３対の超音波送受信器による各対気速度の計測値ｕsen，ｖsen，ｗsenをセンサ座標系に変換する行列であり、下記の式（１２）及び式（１３）で表される。
Also, rotate the sensor coordinate system by θ 1 around the z sen axis, rotate the resulting coordinate system x 1 y 1 z 1 by θ 2 around the y 1 axis, and rotate the resulting coordinate system x 2 y Set the aircraft coordinate system xyz, which is created by rotating 2 z 2 by θ 3 around the y 2 axis.
In FIG. 8, the propagation paths of the two ultrasonic transceivers 6, 7, 9, and 10, except for the pair of ultrasonic transceivers 4 and 5, in which the ultrasonic propagation path is in the x sen axis direction and the y sen Let the angles with the axis be θ 1 and θ 2 .
Furthermore, the airspeed measurements by the three pairs of ultrasonic transceivers are defined as u sen , v sen , and w sen , respectively, and the angle between the x-axis and the airspeed vector around the z-axis is β, which is the xy plane. If the angle formed with the airspeed vector is α, then the x-direction component u, the y-direction component v, the z-direction component w of the measured airspeed value, the measured value of the airspeed magnitude Vsen , and the measurement of the wind direction. The values β and α are expressed by the following equations (8) to (11).
β=arctan(v/u)...Formula (10)
α=arctan {w/(u 2 + v 2 ) 1/2 }...Formula (11)
However, R xyz sen is a rotation matrix that converts the aircraft coordinate system to the sensor coordinate system, and R sen is the rotation matrix that converts each airspeed measurement value u sen , v sen , and w sen from the three pairs of ultrasonic transceivers into the sensor coordinate system. It is a matrix to be converted into , and is expressed by the following equations (12) and (13).
小型ＵＡＶの対気速度及び風向の計測では、小型ＵＡＶの飛行が制御されていて水平飛行しており、風向がある程度分かっている場合等、二次元情報のみで十分な場合がある。
二次元情報を得るために、２対の超音波送受信器を用いる。一方の超音波送受信器の超音波の伝播経路の方向をｘsen軸とし、ｘsen軸に対して右手直交系をなすようにｙsen軸を決めることで、センサ座標系を設定する。
また、センサ座標系をθ1だけ回転させてできる機体座標系ｘｙを設定する。２対の超音波送受信器を用いた対気速度の二次元情報を示す図を図１０に示す。超音波の伝播経路がｘsen軸方向の１対の超音波送受信器４，５でない、他方の１対の超音波送受信器６，７の各伝播経路とｙsen軸とのなす角をθ1とする。
さらに、２対の超音波送受信器による対気速度の計測値を、それぞれｕsen，ｖsenとし、ｘ軸と対気速度ベクトルとのなす角をβとすると、対気速度の計測値のｘ方向成分ｕ、ｙ方向成分ｖ、対気速度の大きさの計測値Ｖsen及び風向の計測値βは、下記の式（１４）～（１６）で表される。
β＝arctan（ｖ／ｕ）・・・・・・式（１６）
特に、対気速度及び風向の三次元情報又は二次元情報を得る時、それぞれの超音波送受信器の伝播経路が直交する場合、すなわち、三次元情報を得る時のθ1＝０°，θ2＝９０°又は二次元情報を得る時のθ1＝０°である場合、式（１３）及び式（１４）は簡単になり、演算する上で有利である。
In measuring the airspeed and wind direction of a small UAV, only two-dimensional information may be sufficient, such as when the small UAV is flying in a controlled and horizontal manner and the wind direction is known to some extent.
Two pairs of ultrasound transceivers are used to obtain two-dimensional information. The sensor coordinate system is set by setting the direction of the ultrasonic propagation path of one ultrasonic transmitter/receiver as the x sen axis, and determining the y sen axis to form a right-handed orthogonal system to the x sen axis.
In addition, the body coordinate system xy, which is created by rotating the sensor coordinate system by θ 1 , is set. A diagram showing two-dimensional information on airspeed using two pairs of ultrasonic transceivers is shown in FIG. The angle between each propagation path of the other pair of ultrasonic transceivers 6 and 7 and the y sen axis is θ 1 shall be.
Furthermore, if the airspeed measurements by the two pairs of ultrasonic transceivers are u sen and v sen , respectively, and the angle between the x-axis and the airspeed vector is β, then the airspeed measurement value x The direction component u, the y-direction component v, the measured value V sen of the airspeed, and the measured value β of the wind direction are expressed by the following equations (14) to (16).
β=arctan(v/u)...Formula (16)
In particular, when obtaining three-dimensional or two-dimensional information on airspeed and wind direction, if the propagation paths of the respective ultrasonic transceivers are orthogonal, that is, when obtaining three-dimensional information, θ 1 =0°, θ 2 =90° or when θ 1 =0° when obtaining two-dimensional information, equations (13) and (14) become simple and are advantageous in calculation.
複数対の超音波送受信器の取り付けについて、各対の超音波送受信器の距離は同じである必要はないが、同じであれば対気速度及び風向を算出する演算の処理が簡便である。
また、超音波送受信器が超音波を検出できる範囲であれば、各対の超音波送受信器の距離に制限はないが、超音波送受信器の外形の寸法に対して、各対の超音波送受信器の間の距離が十分大きくない場合、計測する流れの内、超音波送受信器及びその支持具等によって乱される流れの割合が大きくなって、対気速度及び風向の計測誤差が大きくなる。
さらに、取り付ける航空機の機体の外形の寸法を大きく超える距離の場合、超音波送受信器及びその支持具等が航空機の飛行特性を大きく悪化させる原因となる。
そのため、各対の超音波送受信器の間の距離は、超音波送受信器の外形の寸法より十分大きく、取り付ける航空機の外形の寸法を超えない範囲が望ましい。
Regarding the installation of multiple pairs of ultrasonic transceivers, it is not necessary that the distances between the ultrasonic transceivers of each pair be the same, but if they are the same, the calculation process for calculating the airspeed and wind direction will be easier.
There is no limit to the distance between each pair of ultrasonic transmitters and receivers as long as the ultrasonic transmitter and receiver can detect ultrasonic waves, but the distance between each pair of ultrasonic transmitters and receivers is If the distance between the instruments is not large enough, a large proportion of the flow to be measured will be disturbed by the ultrasonic transmitter/receiver and its support, resulting in large errors in measuring airspeed and wind direction.
Furthermore, if the distance greatly exceeds the external dimensions of the aircraft body to which the ultrasonic transmitter/receiver is attached, the ultrasonic transmitter/receiver, its support, etc. will greatly deteriorate the flight characteristics of the aircraft.
Therefore, it is desirable that the distance between each pair of ultrasonic transceivers be sufficiently larger than the external dimensions of the ultrasonic transceivers, and within a range that does not exceed the external dimensions of the aircraft to which they are attached.
本発明の対気速度を計測する対象の小型ＵＡＶは、実施例１のような回転翼タイプと、図１１に示すような固定翼タイプのものに大別される。
回転翼タイプの小型ＵＡＶの場合、物資の運搬を目的とする機体では、機体の下部は物資を積載するスペースとして確保し、機体の外形に対称性を持つ機体では、飛行特性の観点から機体の外形の対称性を崩ないように、超音波送受信器を取り付けると良い。
一例として、回転翼の小型ＵＡＶには、位置や速度情報を取得するために、全球測位衛星システム（ＧＮＳＳ：Global Navigation Satellite System）の受信器が機体の上部に搭載されているものがあり、実施例１では受信機部分に超音波送受信器を取り付けている。
固定翼の小型ＵＡＶは、プロペラ等から推進力を得て、操舵翼を操舵して飛行する。プロペラから推進力を得る場合、プロペラ後流が超音波の伝播経路に入ると、対気速度及び風向に計測誤差が生まれる。そのため、超音波の伝播経路がプロペラ後流に晒されないように、超音波送受信器を取り付ける。また、固定翼の小型ＵＡＶの対気速度は、機首方向の成分が大きいため、機首方向の流れをセンサプローブが乱さないように、超音波の伝播経路が機首方向と平行にならないように超音波送受信器を配置する。
一例として、双発の固定翼の小型ＵＡＶは、機軸の周辺がプロペラ後流に晒されにくいので、図１１ではその部分に超音波送受信器を取り付けている。
また、本発明は、伝播時間差を利用して計測される対気速度と同等の計測範囲で、高い分解能の対気速度の計測ができるため、小型ＵＡＶだけでなく有人の航空機に対しても適用できる。
The small UAVs whose airspeeds are to be measured according to the present invention are broadly classified into rotary wing types as in Example 1 and fixed wing types as shown in FIG. 11.
In the case of small rotary-wing type UAVs, if the purpose is to transport goods, the lower part of the fuselage should be reserved as a space for loading supplies, and if the aircraft has a symmetrical external shape, the lower part of the fuselage should be set aside from the viewpoint of flight characteristics. It is best to attach an ultrasonic transmitter/receiver so as not to disrupt the symmetry of the external shape.
For example, some small rotary-wing UAVs are equipped with a Global Navigation Satellite System (GNSS) receiver mounted on top of the aircraft to obtain position and speed information. In Example 1, an ultrasonic transceiver is attached to the receiver section.
A small fixed-wing UAV obtains propulsion power from a propeller or the like and flies by steering the control blades. When propulsive force is obtained from a propeller, if the propeller wake enters the ultrasonic propagation path, measurement errors will occur in airspeed and wind direction. Therefore, the ultrasonic transceiver is installed so that the ultrasonic propagation path is not exposed to the wake of the propeller. In addition, the airspeed of small fixed-wing UAVs has a large component in the nose direction, so in order to prevent the sensor probe from disturbing the flow in the nose direction, the ultrasonic propagation path should not be parallel to the nose direction. Place the ultrasonic transmitter/receiver at
As an example, since the area around the axis of a small twin-engine fixed-wing UAV is less likely to be exposed to the wake of the propeller, an ultrasonic transceiver is attached to that area in FIG. 11.
In addition, the present invention can measure airspeed with high resolution in the same measurement range as airspeed measured using propagation time differences, so it is applicable not only to small UAVs but also to manned aircraft. can.
小型ＵＡＶに取り付けられた１対の超音波送受信器の一方から送信した超音波は、空気中を伝播する他、超音波送受信器の支持具等を伝播し、他方の超音波送受信機が受信する。
本発明では、超音波が１対の超音波送受信器の間の空気中を伝播して、その受信信号から対気速度及び風向を算出する。そのため、超音波送受信器の支持具等を伝播した超音波を受信すると、対気速度及び風向の計測誤差の原因となる。
一般的に、このような意図しない超音波の伝播を防止するため、超音波送受信器と意図しない超音波の伝播経路を吸音材で仕切れば良い。
しかし、小型ＵＡＶの対気速度及び風向の計測では、超音波送受信器及びその支持具等によって、計測したい流れを乱すことや、小型ＵＡＶの飛行特性を悪化させることは避けらず、これらの影響を抑える上で、吸音材は妨げになる。
そこで、超音波送受信器の支持具の超音波の伝播に関するパラメータの同定により、超音波送受信器の支持具を伝播した超音波を受信することによる、対気速度及び風向の計測誤差を除去する。
同定されるパラメータは、送信側の超音波送受信器から発せられた超音波が支持具を伝播して受信側の超音波送受信器によって受信されるときに生じるもので、超音波の受信信号に含まれており対気速度の測定誤差の原因となるパラメータである。このため計測する流れ方向及び流れと逆方向に超音波が伝播したときの受信信号と正弦波との位相差を算出する際に、逆正接を計算する分母と分子にそれぞれ１つずつパラメータが生じる。
超音波が超音波送受信器の支持具を伝播して受信したことによる計測誤差を含んだ、受信信号α１と周波数ｆの正弦波の位相差φ1は、ω＝２πｆとして下記の式（１７）で表される。
位相差φ2も、超音波が超音波送受信器の支持具を伝播して受信した電圧信号をＡ2’＞０でＡ2’ｓｉｎ（ωｔ＋φ2’）と仮定して、対気速度及び風向の計測誤差の原因となるパラメータをＥs2，Ｅｃ2とすれば、式（１７）のφ1をφ2に置き換えて同様に計算される。
パラメータＥs1，Ｅｃ1，Ｅs2，Ｅｃ2を同定しておくことで、超音波送受信器の支持具を伝播した超音波を受信することによる対気速度及び風向の計測誤差を除去できる。
以上の説明は、１対の超音波送受信器を用いた場合の対気速度及び風向の計測誤差の原因となるパラメータの除去方法であったが、２対及び３対の超音波送受信器を用いた場合も、それぞれ独立に対気速度及び風向の計測を、１対の超音波送受信器の対気速度及び風向の計測方法で行っているから、それぞれ対気速度及び風向の計測誤差の原因となるパラメータを除去すれば、それぞれ誤差を除去でき、２対及び３対の超音波送受信器を用いた対気速度及び風向の計測誤差を除去できる。
Ultrasonic waves transmitted from one of a pair of ultrasonic transceivers attached to a small UAV propagate through the air and through the support of the ultrasonic transceiver, and are received by the other ultrasonic transceiver. .
In the present invention, ultrasonic waves propagate in the air between a pair of ultrasonic transceivers, and airspeed and wind direction are calculated from the received signals. Therefore, when receiving ultrasonic waves propagated through the support of an ultrasonic transmitter/receiver, etc., it causes measurement errors in airspeed and wind direction.
Generally, in order to prevent such unintended propagation of ultrasonic waves, the ultrasonic transmitter/receiver and the propagation path of unintended ultrasonic waves may be partitioned off with a sound absorbing material.
However, when measuring the airspeed and wind direction of a small UAV, it is unavoidable that the ultrasonic transmitter/receiver and its support equipment disturb the flow to be measured and deteriorate the flight characteristics of the small UAV. Sound-absorbing materials can be a hindrance to suppressing noise.
Therefore, by identifying parameters related to the propagation of ultrasonic waves through the support of the ultrasonic transceiver, errors in measuring airspeed and wind direction due to reception of ultrasonic waves propagated through the support of the ultrasonic transceiver are removed.
The identified parameters are those that occur when the ultrasonic waves emitted from the ultrasonic transceiver on the transmitting side propagate through the support and are received by the ultrasonic transceiver on the receiving side, and are included in the received ultrasonic signal. This is a parameter that causes airspeed measurement errors. Therefore, when calculating the phase difference between the received signal and the sine wave when the ultrasonic wave propagates in the flow direction to be measured and in the opposite direction to the flow, one parameter is generated for the denominator and numerator for calculating the arctangent. .
The phase difference φ 1 between the received signal α 1 and the sine wave of frequency f, which includes a measurement error due to the ultrasonic wave being received after propagating through the support of the ultrasonic transmitter/receiver, is expressed by the following equation (17) with ω = 2πf. It is expressed as
The phase difference φ 2 is also determined by the airspeed and wind direction, assuming that the voltage signal received by the ultrasonic wave propagating through the support of the ultrasonic transmitter/receiver is A 2 ′ > 0 and A 2 ′ sin (ωt + φ 2 ′). Let E s2 and E c2 be the parameters that cause the measurement error in Eq.
By identifying the parameters E s1 , E c1 , E s2 , and E c2 , it is possible to eliminate measurement errors in airspeed and wind direction caused by receiving ultrasonic waves propagated through the support of the ultrasonic transmitter/receiver.
The above explanation was about how to remove parameters that cause airspeed and wind direction measurement errors when one pair of ultrasonic transceivers is used, but when using two or three pairs of ultrasonic transceivers, Even in cases where airspeed and wind direction are measured independently, airspeed and wind direction are measured independently using a pair of ultrasonic transmitter/receiver, which may be the cause of measurement errors in airspeed and wind direction, respectively. By removing these parameters, the respective errors can be removed, and the errors in measuring airspeed and wind direction using two and three pairs of ultrasonic transceivers can be removed.
３対の超音波送受信器による対気速度及び風向の計測システム及びその計測システムを用いる対気速度及び風向の計測方法について図１２を用いて説明する。
計測システムは、超音波送受信器と送受信切り替えユニット、受信信号増幅ユニット、マイクロコンピュータから構成される。
１対の超音波送受信器は、それぞれが印加された電圧信号から超音波を送信する及び超音波を受信して電圧信号を発生する機能を持つ。
送受信切り替えユニットは、超音波送受信器に超音波の送信をさせるか、または超音波を受信させるかのいずれかに切り替える機能を持つ。
受信信号増幅ユニットは、超音波送受信器が超音波を受信して発生した電圧信号を増幅する機能を持つ。
マイクロコンピュータは、超音波を送信する超音波送受信機に印加する電圧信号を発生する回路と、受信信号増幅ユニットにより増幅された受信信号をＡ／Ｄ変換してデジタル化する回路、デジタル化された受信信号から対気速度及び風向を算出するＣＰＵ、外部システムと通信して算出した対気速度及び風向データを送信する回路からなる。
マイクロコンピュータにより、超音波送受信器に印加する電圧信号を生成し、送受信切り替えユニットにより超音波を送信する機能に指定された超音波送受信器に印加される。
送受信切り替えユニットにより、超音波を受信する機能に指定された超音波送受信器が送信された超音波を受信して電圧信号を生成し、受信信号増幅ユニットにより受信した受信信号が増幅される。
そして、マイクロコンピュータにより、増幅された受信信号をＡ／Ｄ変換してデジタル化し、デジタル化された受信信号から対気速度及び風向を算出して、外部システムに対気速度及び風向データを送信する。
外部システムは、対気速度及び風向データを必要とするシステムであり、小型ＵＡＶの自律飛行制御の場合、得られた対気速度及び風向のデータを用いてアクチュエータの指令値を決定し、アクチュエータを動かすシステムを指す。
A system for measuring airspeed and wind direction using three pairs of ultrasonic transceivers and a method for measuring airspeed and wind direction using the measurement system will be described with reference to FIG. 12.
The measurement system consists of an ultrasonic transceiver, a transmission/reception switching unit, a received signal amplification unit, and a microcomputer.
The pair of ultrasonic transceivers each have the function of transmitting ultrasonic waves from an applied voltage signal and receiving ultrasonic waves to generate a voltage signal.
The transmission/reception switching unit has a function of switching the ultrasonic transceiver to either transmit ultrasonic waves or receive ultrasonic waves.
The received signal amplification unit has a function of amplifying the voltage signal generated by the ultrasonic transceiver receiving ultrasonic waves.
A microcomputer consists of a circuit that generates a voltage signal to be applied to an ultrasonic transmitter/receiver that transmits ultrasonic waves, a circuit that converts the received signal amplified by a received signal amplification unit into digital form by A/D converting it, and a circuit that converts the received signal into a digital signal. It consists of a CPU that calculates airspeed and wind direction from received signals, and a circuit that communicates with an external system and transmits the calculated airspeed and wind direction data.
The microcomputer generates a voltage signal to be applied to the ultrasound transceiver, and the transmission/reception switching unit applies the voltage signal to the ultrasound transceiver designated for the function of transmitting ultrasound.
The transmission/reception switching unit causes the ultrasound transceiver designated to receive the ultrasound to receive the transmitted ultrasound and generate a voltage signal, and the reception signal amplification unit amplifies the received signal.
Then, the microcomputer converts the amplified reception signal into digital form, calculates airspeed and wind direction from the digitized reception signal, and sends the airspeed and wind direction data to an external system. .
The external system is a system that requires airspeed and wind direction data, and in the case of autonomous flight control of a small UAV, the obtained airspeed and wind direction data is used to determine the command value of the actuator and control the actuator. Refers to the system that moves.
計測器は、標準器で計測して得た値を真の値の推定値として校正を行う必要がある。
実施例３の特徴は、小型ＵＡＶの自律制御を目的とした低速領域の対気速度及び風向を計測することにあり、中心周波数４０ｋＨｚの超音波送受信器（UT1612MPR/UR1612MPR，CPL (Hong Kong) Limited）を用いて、従来の小型ＵＡＶ用風向風速計では計測できない４ｍ／秒以下の対気速度に対して校正を行った。
校正手法として、インクリメンタル型ロータリエンコーダにより対地速度を計測できる手押し車に、計測器を搭載して人力で走行し、静止した空気中で対地速度と対気速度が等しくなることを利用した。
これは、産業技術総合研究所（https://unit.aist.go.jp/riem/gfstd/facility.html）による、地下トンネル内で微風速計を載せた台車を走行させる校正施設を模したものである。
Measuring instruments need to be calibrated using the values obtained by measuring with standard instruments as estimates of the true values.
The feature of Embodiment 3 is to measure the airspeed and wind direction in a low speed region for the purpose of autonomous control of a small UAV, and it uses an ultrasonic transceiver (UT1612MPR/UR1612MPR, CPL (Hong Kong) Limited) with a center frequency of 40kHz. ) was used to calibrate airspeeds of 4 m/s or less, which cannot be measured with conventional small UAV anemometers.
As a calibration method, we installed a measuring device in a wheelbarrow that can measure ground speed using an incremental rotary encoder and drove it manually, taking advantage of the fact that ground speed and air speed are equal in still air.
This is a calibration facility designed by the National Institute of Advanced Industrial Science and Technology (https://unit.aist.go.jp/riem/gfstd/facility.html) that runs a trolley carrying a microanemometer inside an underground tunnel. It is something.
マイクロコンピュータ（dePIC33FJ64GP802，Microchip Technology）により、１０周期の電圧差３．３Ｖp-pで４０ｋＨｚの矩形波の電圧信号を生成し、３ステートバッファ（SN74HC125N，TEXAS INSTRUMENTS）とアナログスイッチ（TC74HC4066AP，TOSHIBA）からなる送受信切り替えユニットにより、超音波を送信する機能に指定された超音波送受信器に印加される。
送受信切り替えユニットにより、超音波を受信する機能に指定された超音波送受信器が、送信された超音波を受信して電圧信号を生成し、オペアンプ（NJM2732D，新日本無線株式会社）を用いた反転増幅回路からなる受信信号増幅ユニットにより、受信した受信信号が増幅される。
マイクロコンピュータにより、増幅された受信信号をサンプリング周波数４００ｋＨｚでＡ／Ｄ変換してデジタル化し、デジタル化された受信信号から対気速度及び風向を算出して、外部システム（Arduino Micro，Arduino Srl）に対気速度及び風向データをＩ２Ｃ通信で送信する。
A microcomputer (dePIC33FJ64GP802, Microchip Technology) generates a 40kHz square wave voltage signal with a 10-cycle voltage difference of 3.3V pp , and consists of a 3-state buffer (SN74HC125N, TEXAS INSTRUMENTS) and an analog switch (TC74HC4066AP, TOSHIBA). The transmitting/receiving switching unit applies the voltage to the ultrasound transceiver designated for the function of transmitting ultrasound.
The ultrasonic transmitter/receiver designated to receive ultrasonic waves by the transmission/reception switching unit receives the transmitted ultrasonic waves, generates a voltage signal, and inverts the signal using an operational amplifier (NJM2732D, New Japan Radio Co., Ltd.). A received signal is amplified by a received signal amplification unit including an amplifier circuit.
A microcomputer converts the amplified received signal into digital data at a sampling frequency of 400kHz, calculates airspeed and wind direction from the digitized received signal, and sends it to an external system (Arduino Micro, Arduino Srl). Transmits airspeed and wind direction data via I2C communication.
外部システムは、小型ＵＡＶの自律制御で対気速度を参照した制御手法の実装において必要と思われるサンプリング周波数１０Ｈｚで対気速度を計測し校正を行った。
それぞれ距離Ｌ＝１５０ｍｍで、θ1＝０°、すなわち、それぞれの伝播経路が直交して設置された２対の超音波送受信器を用いて、二次元の対気速度の大きさの計測値Ｖsenを、ロータリエンコーダによる対地速度の計測値Ｖreを対気速度の真の値の推定値として、θ1＝０°で機体座標系を設定した時のβ＝４５°について校正した結果を図１３に示す。
校正する前の小型ＵＡＶ用超音波風向微風速計による対気速度の計測値は、ロータリエンコーダによる対地速度の計測値に対して、およそ３０％の計測誤差が生じることが分かり、超音波送受信器の支持具等を伝播した超音波を受信することによる対気速度の計測誤差を除去した。
校正した結果から、サンプリング周波数１０Ｈｚで、小型ＵＡＶの自律制御に用いるに十分な分解能で、対気速度や風向を計測できることが分かった。
The external system measured and calibrated airspeed at a sampling frequency of 10 Hz, which is considered necessary for implementing a control method that refers to airspeed in autonomous control of a small UAV.
Using two pairs of ultrasonic transceivers installed at a distance L = 150 mm and θ 1 = 0°, that is, their respective propagation paths are orthogonal, the two-dimensional airspeed magnitude is measured V The figure shows the results of calibration for β = 45° when the aircraft coordinate system is set at θ 1 = 0°, with sen as the ground speed measurement value V re measured by the rotary encoder as the estimated value of the true value of airspeed. 13.
It was found that the airspeed measurements made by the ultrasonic anemometer for small UAVs before calibration had a measurement error of approximately 30% compared to the ground speed measurements made by the rotary encoder. Airspeed measurement errors caused by receiving ultrasonic waves propagated through supports, etc., have been eliminated.
The calibration results showed that airspeed and wind direction can be measured at a sampling frequency of 10Hz with sufficient resolution for autonomous control of small UAVs.
校正した小型ＵＡＶ用超音波風向微風速計を搭載した双発の固定翼の小型ＵＡＶを、旋回半径を一定とする旋回飛行の制御を実装した上で飛行し、その時の対気速度及び風向を計測した。
小型ＵＡＶ用超音波風向微風速計は、それぞれ距離Ｌ＝１５０ｍｍでθ1＝０°，θ2＝９０°、すなわち、それぞれの伝播経路が直交して設置された３対の超音波送受信器を用いて、機体の機首方向をｘ軸、左右方向をｙ軸、ｘ軸に垂直な胴体の上下方向をｚ軸とする機体座標系を設定して、センサ座標系がθ1＝０°，θ2＝０°となるように、機体に３対の超音波送受信器を設置した。
旋回半径を一定とする旋回飛行の制御ループの制御周期が２０ミリ秒であったため、サンプリング周波数５０Ｈｚで対気速度及び風向を計測した。
飛行試験における対気速度ｕ，ｖ，ｗ，Ｖ及び風向α，βの計測結果を図１４に示す。これらの飛行試験における対気速度や風向の計測の結果から、本発明によれば低速で飛行する小型ＵＡＶの対気速度及び風向を計測できることが分かった。
A small, twin-engine fixed-wing UAV equipped with a calibrated ultrasonic wind direction and microanemometer for small UAVs is flown with control for turning flight with a constant turning radius, and the airspeed and wind direction are measured at that time. did.
The ultrasonic anemometer for small UAV has three pairs of ultrasonic transmitters and receivers installed at a distance L = 150 mm and θ 1 = 0°, θ 2 = 90°, that is, their respective propagation paths are orthogonal. Using this, we set an aircraft coordinate system in which the nose direction of the aircraft is the x axis, the horizontal direction is the y axis, and the vertical direction of the fuselage perpendicular to the x axis is the z axis, so that the sensor coordinate system is θ 1 = 0°, Three pairs of ultrasonic transceivers were installed on the aircraft so that θ 2 =0°.
Since the control cycle of the control loop for turning flight with a constant turning radius was 20 milliseconds, airspeed and wind direction were measured at a sampling frequency of 50 Hz.
Figure 14 shows the measurement results of airspeeds u, v, w, V and wind directions α, β in the flight test. From the results of measuring airspeed and wind direction in these flight tests, it was found that according to the present invention, the airspeed and wind direction of a small UAV flying at low speed can be measured.
実施例１及び２の飛行体用対気速度及び風向計測装置及びその計測方法に関する変形例を列記する。
（１）実施例１及び２では、第１伝播時間計測手段１１、２１及び第２伝播時間計測手段１２，２２で伝播時間を計測し、時間差風速を演算したが、位相差を演算する時と同様に第１受信信号及び第２受信信号を記録した上で、第１伝播時間及び第２伝播時間を計測し、時間差風速を演算しても良い。
（２）実施例１及び２では、・・・でも良い。
（３）実施例１及び２では、・・・でも良い。
Modifications regarding the airspeed and wind direction measuring device for aircraft and the measuring method of Examples 1 and 2 will be listed.
(1) In Examples 1 and 2, the first propagation time measuring means 11 and 21 and the second propagation time measuring means 12 and 22 measured the propagation time and calculated the time difference wind speed, but when calculating the phase difference Similarly, after recording the first received signal and the second received signal, the first propagation time and the second propagation time may be measured to calculate the time difference wind speed.
(2) In Examples 1 and 2,... may be used.
(3) In Examples 1 and 2,... may be used.
１ 第１風速計測手段 ２ 第２風速計測手段 ３ 風向計測手段
４、６、９ 一方の超音波送受信器 ５、７、１０ 他方の超音波送受信器
８ 第３風速計測手段 １１、２１ 第１伝播時間計測手段
１２、２２ 第２伝播時間計測手段 １３ 時間差風速演算手段
１４、２４ 第１受信信号記録手段 １５、２５ 第２受信信号記録手段
１６、２６ 位相差演算手段 １７、２７ 位相差修正手段
１８、２８ 位相差風速演算手段
ｆ 中心周波数（Ｈｚ） Ｌ １対の超音波送受信器間の距離
ｔ 時間（秒） ｔ1、ｔ3 第１伝播時間（秒） ｔ2、ｔ4 第２伝播時間（秒）
Ｖｐ、Ｖ1p、Ｖ2p 位相差風速（ｍ／秒） Ｖｓ 音速（ｍ／秒）
ｕ、ｕsen 対気速度の計測値のｘ方向成分（ｍ／秒）
ｖ、ｖsen 対気速度の計測値のｙ方向成分（ｍ／秒）
ｗ、ｗsen 対気速度の計測値のｚ方向成分（ｍ／秒）
Ｖ、Ｖsen 対気速度の大きさの計測値（ｍ／秒） α、β 風向の計測値（ｒａｄ）
α1、α2 第１受信信号 β1、β2 第２受信信号
θ1、θ2、θ3 回転角度（ｒａｄ） φ１、φ２ 位相差（ｒａｄ）
φ1a、φ2a 修正位相差（ｒａｄ） φ1、φ2 正弦波との位相差（ｒａｄ）
Ｒxyz
sen 機体座標系からセンサ座標系に変換する回転行列
Ｒsen 各対気速度の計測値ｕsen，ｖsen，ｗsenをセンサ座標系に変換する行列
1 First wind speed measuring means 2 Second wind speed measuring means 3 Wind direction measuring means 4, 6, 9 One ultrasonic transceiver 5, 7, 10 Other ultrasonic transceiver 8 Third wind speed measuring means 11, 21 First propagation Time measurement means 12, 22 Second propagation time measurement means 13 Time difference wind speed calculation means 14, 24 First received signal recording means 15, 25 Second reception signal recording means 16, 26 Phase difference calculation means 17, 27 Phase difference correction means 18 , 28 Phase difference wind speed calculation means f Center frequency (Hz) L Distance t between a pair of ultrasonic transceivers Time (seconds) t 1 , t 3 First propagation time (seconds) t 2 , t 4 Second propagation time (seconds)
Vp, V1p, V2p Phase difference wind speed (m/sec) Vs Sound speed (m/sec)
u, u sen x-direction component of measured airspeed (m/s)
v, v sen y-direction component of measured airspeed (m/s)
w, w sen Z-component of measured airspeed (m/s)
V, V sen Measured value of airspeed (m/sec) α, β Measured value of wind direction (rad)
α1, α2 First received signal β1, β2 Second received signal θ 1 , θ 2 , θ 3 Rotation angle (rad) φ1, φ2 Phase difference (rad)
φ1a, φ2a Corrected phase difference (rad) Phase difference with φ 1 , φ 2 sine wave (rad)
R xyz sen Rotation matrix for converting from the aircraft coordinate system to the sensor coordinate system R sen Matrix for converting each airspeed measurement value u sen , v sen , w sen to the sensor coordinate system
Claims (3)
前記第１風速計測手段で計測された第１の方向についての風速及び前記第２風速計測手段で計測された第２の方向についての風速に基づいて風向を計測する風向計測手段を備え、
前記第１風速計測手段及び前記第２風速計測手段は、いずれも
１対の超音波送受信器と、
一方の超音波送受信器が超音波を送信してから他方の超音波送受信器で該超音波を受信するまでの第１伝播時間を計測する第１伝播時間計測手段と、
前記他方の超音波送受信器が超音波を送信してから前記一方の超音波送受信器で該超音波を受信するまでの第２伝播時間を計測する第２伝播時間計測手段と、
前記第１伝播時間計測手段で計測された第１伝播時間及び前記第２伝播時間計測手段で計測された第２伝播時間に基づいて時間差風速を演算する時間差風速演算手段と、
前記一方の超音波送受信器が超音波を送信した後、前記他方の超音波送受信器で受信した第１受信信号を記録する第１受信信号記録手段と、
前記他方の超音波送受信器が超音波を送信した後、前記一方の超音波送受信器で受信した第２受信信号を記録する第２受信信号記録手段と、
前記第１受信信号記録手段で記録された第１受信信号と前記第２受信信号記録手段で記録された第２受信信号との位相差を演算する位相差演算手段と、
前記時間差風速演算手段で演算された風速及び前記超音波送受信器の支持具の超音波の伝播に関するパラメータに基づいて、前記位相差演算手段で演算された位相差を修正する位相差修正手段と、
前記位相差修正手段で修正された修正位相差に基づいて位相差風速を演算する位相差風速演算手段を有している
ことを特徴とする飛行体用対気速度及び風向計測装置。 A first wind speed measuring means for measuring wind speed in a first direction and a second wind speed measuring means for measuring wind speed in a second direction different from the first direction, on the outer surface of the flying object;
Wind direction measuring means for measuring the wind direction based on the wind speed in the first direction measured by the first wind speed measuring means and the wind speed in the second direction measured by the second wind speed measuring means,
The first wind speed measuring means and the second wind speed measuring means each include a pair of ultrasonic transceivers,
a first propagation time measuring means for measuring a first propagation time from when one ultrasonic transceiver transmits an ultrasonic wave until the other ultrasonic transceiver receives the ultrasonic wave;
a second propagation time measuring means for measuring a second propagation time from when the other ultrasonic transceiver transmits an ultrasonic wave until the one ultrasonic transceiver receives the ultrasonic wave;
time difference wind speed calculation means for calculating a time difference wind speed based on a first propagation time measured by the first propagation time measurement means and a second propagation time measured by the second propagation time measurement means;
a first received signal recording means for recording a first received signal received by the other ultrasonic transceiver after the one ultrasonic transceiver transmits the ultrasonic wave;
a second received signal recording means for recording a second received signal received by the one ultrasonic transceiver after the other ultrasonic transceiver transmits the ultrasonic wave;
phase difference calculating means for calculating a phase difference between a first received signal recorded by the first received signal recording means and a second received signal recorded by the second received signal recording means;
a phase difference correction means for correcting the phase difference calculated by the phase difference calculation means based on the wind speed calculated by the time difference wind speed calculation means and a parameter regarding the propagation of the ultrasonic wave of the support of the ultrasonic transmitter/receiver ;
An airspeed and wind direction measuring device for an aircraft, comprising: a phase difference wind speed calculation means for calculating a phase difference wind speed based on the corrected phase difference corrected by the phase difference correction means.
ことを特徴とする請求項１に記載の飛行体用対気速度及び風向計測装置。 The airspeed and wind direction measuring device for an aircraft according to claim 1, wherein the first direction and the second direction are perpendicular to each other within the same plane.
前記第１風速計測手段及び前記第２風速計測手段が、それぞれ有している１対の超音波送受信器のうちの一方の超音波送受信器が超音波を送信してから他方の超音波送受信器で該超音波を受信するまでの第１伝播時間を計測し、
前記一方の超音波送受信器が超音波を送信した後、前記他方の超音波送受信器で受信した第１受信信号を記録し、
前記他方の超音波送受信器が超音波を送信してから前記一方の超音波送受信器で該超音波を受信するまでの第２伝播時間を計測し、
前記他方の超音波送受信器が超音波を送信した後、前記一方の超音波送受信器で受信した第２受信信号を記録し、
前記第１伝播時間及び前記第２伝播時間に基づいて時間差風速を演算し、
前記第１受信信号と前記第２受信信号との位相差を演算し、
前記時間差風速及び前記超音波送受信器の支持具の超音波の伝播に関するパラメータに基づいて前記位相差を修正し、修正位相差を演算し、
前記修正位相差に基づいて位相差風速を演算し、
前記第１風速計測手段で計測された第１の位相差風速及び前記第２風速計測手段で計測された第２の位相差風速に基づいて風向を計測する
ことを特徴とする飛行体用対気速度及び風向計測方法。 A first wind speed measuring means installed on the outer surface of the flying object measures the wind speed in a first direction, and a second wind speed measuring means measures the wind speed in a second direction different from the first direction. , a method for measuring the airspeed and wind direction of the aircraft, the method comprising:
The first wind speed measuring means and the second wind speed measuring means each have a pair of ultrasonic transceivers, after one of the ultrasonic transceivers transmits an ultrasonic wave, the other ultrasonic transceiver transmits an ultrasonic wave. Measure the first propagation time until receiving the ultrasonic wave at
After the one ultrasonic transceiver transmits the ultrasonic wave, recording a first reception signal received by the other ultrasonic transceiver,
Measuring a second propagation time from when the other ultrasonic transceiver transmits the ultrasonic wave until the one ultrasonic transceiver receives the ultrasonic wave,
After the other ultrasonic transceiver transmits the ultrasonic wave, recording a second reception signal received by the one ultrasonic transceiver,
calculating a time difference wind speed based on the first propagation time and the second propagation time;
calculating a phase difference between the first received signal and the second received signal;
correcting the phase difference based on the time difference wind speed and parameters related to the propagation of the ultrasonic wave of the support of the ultrasonic transmitter/receiver , and calculating a corrected phase difference;
calculating a phase difference wind speed based on the corrected phase difference;
An air conditioner for an aircraft, characterized in that wind direction is measured based on a first phase difference wind speed measured by the first wind speed measuring means and a second phase difference wind speed measured by the second wind speed measuring means. Speed and wind direction measurement method.
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