JP6095899B2 - Target motion estimation device, target motion estimation method, and radar device - Google Patents

Description

  The present invention relates to a target motion estimation device that estimates motion of a target based on information about a target such as a ship detected by transmission and reception of electromagnetic waves.

  Hereinafter, the case where this invention is applied to a radar apparatus will be described.

  Conventionally, as this type of device using a radar device as a detection device, for example, an automatic collision prevention assistance device (TT: Target Tracking or ARPA: Automatic Radar Plotting Aid) for the purpose of preventing a collision with a ship or the like. (Hereinafter referred to as TT) is known.

  As shown in FIG. 8, this TT is mainly configured by a signal measurement unit 101, a motion estimation unit 102, and a data display unit 103.

  The signal measuring unit 101 includes an echo signal related to the observation position of a target such as another ship from a radar device (not shown), a gyro signal related to the own ship course in the gyro compass, and a log signal related to the own ship speed from the log device. Based on these input signals, information on the current observation position of the target (in this case, echo data of the target) is created, and the information is output to the motion estimation unit 102.

  The motion estimation unit 102 estimates the motion of the target based on the measurement information sequentially sent from the signal measurement unit 101 in time series, and the data display unit 103 displays information on the estimated predicted position of the target. Output to.

  Based on the estimation information from the motion estimation unit 102, the data display unit 103 displays the target course and speed estimation values for the target, graphic data for a user-friendly display, for example, vector display. Create and display this on the display.

  By the way, the echo data, which is information on the observation position obtained in the signal measuring unit 101, includes noises of clutter and receivers, and there are various disturbances such as fluctuations in the signal from the target itself. included. When such a disturbance is large, an error is also generated in the target motion estimation result in the motion estimation unit 102, and an accurate result cannot be obtained.

  Therefore, according to the conventional technique, the motion estimation unit 102 uses a digital filter such as an αβ tracker or a Kalman filter, performs a moving average, or combines them so that a stable estimation result can be obtained. To reduce the influence of disturbance.

For example, when the motion estimation unit 102 includes an αβ tracker, the following processing is performed. FIG. 9 shows the predicted position of the target for the next (n + 1) th scan from the nth scan of the radar device as a linear predictor with the position smoothing constant α and the velocity smoothing constant β. It shows a state. That is, when the predicted position in the nth scan is X _p (n) and the observation position is X _o (n), the tracking error X _op (n) is
X _op (n) = X _o (n) −X _p (n)
It is. The smoothed position (estimated position) X _s (n) and the smoothed speed (estimated speed) V _s (n) are:
X _s (n) = X _p (n) + α · X _op (n)
V _s (n) = V _s (n−1) + β · X _op (n) / T
It becomes. Here, T is a sample period. From this, the predicted position X _p (n + 1) in the (n + 1) -th scan is
X _p (n + 1) = X _s (n) + V _s (n) · T
Is required. α = 0 is the predicted position, and α = 1 is the observed position. The smaller α is, the stronger the smoothing process is. In practice, echoes that are not related to the tracking target are also input, so a gate that takes into account the allowable range of difference between the predicted position information and the actually input observation position data and the risk of multiple correlations is set at each scan interval. Set to

Japanese Patent No. 3508000 Japanese Patent No. 3629328 JP 2003-337170 A

  In the configuration as described above, the irrelevant echo outside the gate can be excluded by the gate, and noise can be reduced. However, if the observation position information in the gate contains an error, it is based on the observation position information including the error. Since the estimated position and estimated speed are determined, an error occurs in the estimated position and estimated speed for each scan. As a result, the estimated position deviates significantly from the actual position and changes to the estimated speed when a specific target such as a target ship suddenly turns (rapid change of needle) or suddenly changes speed (rapid shift). Even if the filter coefficient is changed according to the frequency, it may not be able to follow the action of the actual specific target. As a result, there are cases in which the tracking target changes to a passing target, the echo of a target in the vicinity (transfer), or a phenomenon that the target being tracked is lost (lost).

  To solve these problems, if the filter coefficient is lightened (α and β are increased), the target vector being tracked will fluctuate even if it is possible to cope with sudden change or sudden change of speed. -There was a problem that it was difficult for the user to see at normal times when there was no sudden shift.

  The present invention has been made in view of such a problem, and is a target motion estimation apparatus that reduces transfer and lost as compared with the prior art and tracks a target with high accuracy.

  According to one aspect of the present invention, an echo signal acquisition unit that acquires an echo signal obtained by reflecting a transmitted electromagnetic wave on a target, and a specific target having a substantially equal distance from the electromagnetic wave transmission source and different directions. Phase change information acquisition unit for acquiring phase change information between two or more echo signals from the target, and target information acquisition for acquiring an observation position of the specific target based on the echo signal acquired by the echo signal acquisition unit , The phase change information obtained by the phase change information acquisition unit, and the observation position information obtained by the target position information acquisition unit, the predicted observation position of the specific target obtained in the next scan There is provided a target motion estimation device including a prediction unit that calculates a predicted position.

  According to another aspect of the present invention, an echo signal obtained by reflecting a transmitted electromagnetic wave on a target is acquired, and the distance from the electromagnetic wave transmission source is approximately the same and has different azimuths. Obtaining phase change information between echo signals, obtaining an observation position of the specific target based on the echo signal, and using the phase change information and the observation position information, obtained in the next scan A target motion estimation method is provided that calculates a predicted position that is an expected observation position of a specific target.

  According to still another aspect of the present invention, an antenna, an echo signal acquisition unit that acquires an echo signal obtained by reflecting an electromagnetic wave transmitted through the antenna by a target, and a distance from the electromagnetic wave transmission source are A phase change information acquisition unit that acquires phase change information between two or more echo signals from a specific target that is substantially the same and different in direction, and based on the echo signal acquired by the echo signal acquisition unit, Using the target information acquisition unit that acquires the observation position, the phase change information obtained by the phase change information acquisition unit, and the observation position information obtained by the target position information acquisition unit, it is obtained in the next scan. There is provided a radar apparatus comprising: a prediction unit that calculates a predicted position that is an expected observation position of the specific target; and a display that displays surrounding information based on the echo signal.

The block diagram which shows an example of a structure of the target motion estimation apparatus in this invention Diagram explaining direct detection The block diagram which shows an example of a structure of the phase change information acquisition part in a target motion estimation apparatus FIG. 3 is a block diagram illustrating an example of a configuration of a prediction unit in the first embodiment The figure which shows an example of the mode of the motion estimation of the target in Embodiment 1 FIG. 9 is a block diagram illustrating an example of a configuration of a prediction unit in the second embodiment The figure which shows an example of the mode of the motion estimation of the target in Embodiment 2 Block diagram showing the configuration of a conventional motion estimation device The figure which shows an example of the mode of the motion estimation of the target in the conventional motion estimation apparatus

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)

  First, an overall configuration of the radar apparatus 10 according to the present embodiment will be described with reference to FIG. In addition, although this embodiment demonstrates as a TT function of the radar apparatus for ships, the use of the target motion estimation apparatus of this invention is not restricted to a TT function.

  As shown in FIG. 1, the radar apparatus 10 includes a radar antenna 1, a transmission / reception unit 2, an A / D conversion unit 3, a target information acquisition unit 4, a phase change information acquisition unit 6, a ship information acquisition unit 7, and a prediction unit. 8. A display device 9 is provided.

  The radar antenna 1 rotates in the same plane with a predetermined rotation period, and the transmission / reception unit 2 is configured to repeatedly transmit and receive electromagnetic wave signals via the radar antenna 1. Here, the time it takes for the echo signal to return after the transmission / reception unit 2 transmits the electromagnetic wave signal can be acquired in polar coordinates centered on the radar antenna 1. Here, a series of operations performed while the radar antenna 1 makes one rotation in the same plane is called “scan”.

  The transmission / reception unit 2 is configured to be able to radiate a directional signal (pulsed radio wave) via the radar antenna 1 and to receive an echo signal from a target around the device itself. . In addition, the transmission / reception part 2 is not restricted to a thing via a rotary antenna. For example, it may be configured by a system (phased array radar) that can shake a beam with the antenna fixed. In this case, a series of operations performed while detecting all the predetermined areas that can be detected is called “scanning”.

  Here, the transmission / reception unit 2 receives unnecessary echo signals such as sea surface reflections and interference signals in addition to the echo signals from the target. Therefore, the echo signal from the target received by the transmission / reception unit 2, the unnecessary echo signal from the sea surface reflection, the interference signal, and the like are collectively referred to as “reception signal”. The received signal includes white noise.

  Further, the transmission / reception unit 2 performs direct detection (IQ phase detection) in order to acquire information on the amplitude and phase of the received signal. By performing direct detection, a complex signal composed of an I signal and a Q signal can be obtained. Here, the direct detection will be described with reference to FIG.

図２に示すように、この受信信号Ｓ（ｔ）は、送受信部２に受信されたあとに２系統に分岐される。そして、一方の受信信号Ｓ（ｔ）に、電磁波信号の搬送波と同一周波数で同一位相の参照信号２ｃｏｓ（２πｆ_０ｔ）を積算して合成することにより、（数２）で表わされる信号を得る。

また、受信信号Ｓ（ｔ）を分岐させた他方に、電磁波の搬送波と同一周波数で位相を９０°ずらした参照信号−２ｓｉｎ（２πｆ_０ｔ）を積算して合成することにより、（数３）で表わされる信号を得る。

（数２）および（数３）の右辺第一項（２倍周波数成分）は、ローパスフィルタ（ＬＰＦ）によって除去される。これにより、送受信部２からは（数４）に示すＩ信号、および（数５）に示すＱ信号が出力される。

It is assumed that the carrier wave of the electromagnetic wave signal transmitted from the radar antenna 1 is a cosine wave having a frequency f0. In this case, if the time after transmitting the electromagnetic wave signal is t and the amplitude of the reception signal input to the transmission / reception unit 2 is X (t), the reception signal S (t) can be expressed by (Equation 1). it can. Here, φ (t) is the phase of the carrier wave of the received signal with respect to the carrier wave of the electromagnetic wave signal. (Hereafter, phase)

As shown in FIG. 2, the received signal S (t) is branched into two systems after being received by the transmission / reception unit 2. Then, the received signal S (t) is integrated with the reference signal 2 cos (2πf ₀ t) having the same frequency and the same frequency as the carrier wave of the electromagnetic wave signal to synthesize, thereby obtaining a signal expressed by (Equation 2). .

Further, by integrating and synthesizing the reference signal −2 sin (2πf ₀ t) whose phase is shifted by 90 ° at the same frequency as the carrier wave of the electromagnetic wave, on the other side of branching the received signal S (t), (Equation 3) A signal represented by

The first term (double frequency component) on the right side of (Expression 2) and (Expression 3) is removed by a low-pass filter (LPF). Thereby, the I signal shown in (Expression 4) and the Q signal shown in (Expression 5) are output from the transmission / reception unit 2.

   The A / D conversion unit 3 converts the analog I signal and Q signal output from the transmission / reception unit 2 into a multi-bit digital signal (IQ reception data), and the target candidate detection unit 41 and the phase change information acquisition unit 6 is output. In addition to the method in which the analog signal I and Q signals are generated by the transmission / reception unit 2 as described above, the digital signal is converted by the A / D conversion unit 3, and the received signal is sampled by the transmission / reception unit 2. The signal I and Q signals may be generated directly. In this case, the A / D conversion unit 3 can be omitted.

  The target information acquisition unit 4 selects an echo signal of a specific target from among the received signals, a target such as a ship, and an echo signal from a reflective object such as a buoy, and specifies the echo signal based on the echo signal. Outputs target information. The target information acquisition unit 4 includes a target candidate detection unit 41 and a target selection unit 42.

  The target candidate detection unit 41 detects an echo signal from a reflection object such as a target such as a ship or a buoy in the received signal, and generates information such as the position, size, and speed of the reflection object. At this time, the detection method of the echo signal from the reflecting object may be any method such as threshold processing of the received signal, detection by shape or size.

  The target sorting unit 42 sorts the specific target tracked and captured in the previous scan by the prediction unit 8 from the plurality of reflectors detected by the target candidate detection unit 41 in the current scan. Specifically, the target being tracked / captured is selected based on a correlation value for each scan such as position, size, or speed.

  The phase change information acquisition unit 6 outputs phase change information based on the phase change amount of the received signal to the prediction unit 8. As shown in FIG. 3, the phase change information acquisition unit 6 includes a sweep memory 61, a phase change amount calculation unit 62, and a speed calculation unit 63.

  The sweep memory 61 is a so-called buffer, and stores IQ reception data of a necessary number of sweeps in real time. Here, “sweep” refers to a series of operations from transmission of an electromagnetic wave signal to transmission of the next electromagnetic wave signal.

  The phase change amount calculation unit 62 calculates the amount of phase change between two points of the received signal that are substantially the same distance from the radar antenna 1 and have different azimuths.

  Based on the phase change amount calculated by the phase change amount calculation unit 62, the speed calculation unit 63 calculates a distance direction component (hereinafter referred to as “Doppler speed”) of the relative speed of a reflective object such as a target, and the calculation result thereof. And the distance direction component of the absolute velocity of the reflecting object such as the target can be calculated based on the ship information input from the ship information acquisition unit 7.

上式から、ｖはそれぞれ次式であらわされる。

Here, a specific calculation method of the phase change amount and the Doppler velocity will be described. The principle of speed measurement using Doppler information is a pulse pair method. Hereinafter, the pulse pair method will be described. The transmission signal is a sinusoidal pulse having a frequency f ₀ , a wavelength λ, and a time width τ, and the beam direction of “the relative velocity vector of the reflector with respect to the antenna” is v. In the following, v is simply referred to as “velocity”, and “direction in which the antenna and reflector are approaching” is referred to as “positive direction of v”. At this time, when the velocity v is measured based on the phase change amount between sweeps, when the transmission repetition interval is represented by T (= 1 / PRF), when the reflector approaches the antenna, the distance between the two is 1 Shortened by vT between sweeps. That is, the round-trip propagation time from the antenna to the reflector is shortened by Δt = 2vT / c (c: speed of light). Therefore, when attention is paid to a series of complex envelope signals (hereinafter referred to as “complex data”) sampled at “time when the same time has elapsed after the start of transmission” in each sweep, the phase change amount Δφ of complex data between adjacent sweeps is It is expressed by the following formula.

From the above equation, v is expressed by the following equation.

であることから生じる現象であり、測定可能な最大相対速度Ｖ_Ｎで速度の折り返しが発生する。速度Ｖ_ｄの算出方法、及び測定可能な最大相対速度Ｖ_Ｎは、次式のようになる。

ここで、速度Ｖ_ｄが折り返し速度以上の場合にパルスペア法で得られる速度Ｖ_ｒは、

となり、正しい速度が得られない。ここでＮ_ｎｕｍは折り返し回数である。 When the absolute value of the phase change amount Δφ is smaller than π, the phase difference (= difference difference) δφ (−π ≦ δφ ≦ π) of the complex data between adjacent sweeps and the phase change amount Δφ match To do. On the other hand, when the absolute value of the amount of phase change is greater than or equal to π, Δφ and δφ do not coincide with each other, the difference between the two becomes an integral multiple of 2π, and the return of speed occurs. If speed wrapping occurs, an accurate speed cannot be obtained. As described above, this is because the Doppler frequency f _dmax that can be measured when the transmission frequency is PRF,

This is a phenomenon that arises from the fact that the return of speed occurs at the maximum relative speed V _N that can be measured. The method of calculating the velocity V _d, and the maximum relative velocity V _N measurable is as follows.

Here, when the speed V _d is equal to or higher than the folding speed, the speed V _r obtained by the pulse pair method is

Therefore, the correct speed cannot be obtained. Here, N _num is the number of turns.

  In the present invention, since the motion of the target is estimated based on the speed change amount instead of the speed, there is little possibility of being affected by the speed return as described above. , May be affected. In this case, it is determined whether or not the Doppler speed is turned back based on the speed change amount due to the change in the position of the target. When it is determined that the Doppler speed is turned back, the speed change amount can be obtained in consideration thereof.

However, in the above-described pulse pair method, the phase change amount and the Doppler velocity can be obtained from (Equation 6) and (Equation 7), but noise is included in the actually observed phase. The Doppler velocity is calculated by using an autocorrelation method improved based on this method.
Here, a method of calculating the phase change amount and the Doppler velocity using the autocorrelation method in this embodiment will be described.

また、１スイープあたりの位相変化量Δθについて次式が成り立つ。

ここでａｒｇ［・］は複素数の偏角を示す。ΔｍとＬは次式を満たす任意の自然数である。

例えば、Δｍ＝Ｌ＝１と選べば次式を得る。

（数１３）を用いて、受信データｚ［ｍ］から位相変化量Δθを推定する方法を自己相関法とよぶ。 In the present embodiment, the phase change amount is calculated by applying the autocorrelation method to the received signal digitally converted by the A / D converter 3 and the received signal stored in the sweep memory 61. Assume that there is an echo whose phase change amount is Δθ. The distance number corresponding to the distance of the target is n ₀ , and the azimuth number of the first direction in which an echo from the target is received is k ₀ . At this time, the adjacent M pieces of received data received from points having substantially the same distance from the radar antenna 1 are respectively represented by S [k ₀ , n ₀ ], S [k _{0 + 1} , n ₀ ], S [k _{0 + 2} , n ₀ ],..., S [k _{0 + M−1} , n ₀ ]. The received data z [m] can be expressed by (Equation 12).

Further, the following equation holds for the phase change amount Δθ per sweep.

Here, arg [•] indicates a complex argument. Δm and L are arbitrary natural numbers satisfying the following expression.

For example, if Δm = L = 1 is selected, the following equation is obtained.

A method of estimating the phase change amount Δθ from the received data z [m] using (Equation 13) is called an autocorrelation method.

この式を相対速度ｖについて解くと次式を得る。

また、（数１３）を（数１７）に代入して次式を得ることができる。

（数１８）を用いて、受信データｚ［ｍ］から相対速度ｖを推定する。 Further, the relative speed can be calculated as follows based on the phase change amount. The round-trip propagation distance from the radar antenna 1 to the target is reduced by 2 vT during the transmission period T when the target approaches at a relative speed v. Therefore, assuming that the frequency of the carrier wave is f ₀ and the speed of light is c, the phase of the received data z [m + 1] is a phase change amount Δθ per sweep expressed by the following equation with respect to the phase of the received data z [m]. Only get bigger.

When this equation is solved for the relative velocity v, the following equation is obtained.

Further, the following equation can be obtained by substituting (Equation 13) into (Equation 17).

(Equation 18) is used to estimate the relative velocity v from the received data z [m].

  The distance direction component of the relative speed between the own apparatus and the target can be calculated based on the amount of phase change of a plurality of received signals having substantially the same distance from the radar antenna 1 and different azimuths by the above-described method.

  The own ship information acquisition unit 7 inputs own ship information including own ship speed information and direction information to the phase change information acquisition unit 6. When the ship is moving with respect to the ground, the speed of the target obtained by the above method is a distance direction component of the relative speed with respect to the ship. Therefore, the distance direction component of the absolute velocity of the target can be obtained by correcting the obtained relative velocity using the own ship information. The own ship information may be any acquisition means such as information obtained from GPS or the like, information based on the speed of the ship relative to the ground (ground speed), heading direction, and heading direction. By calculating the distance direction component of the absolute velocity of the target, tracking / capturing can be performed with higher accuracy with respect to the sudden change of the target and sudden shift. In the present embodiment, the absolute speed is calculated, but the process may be performed with the relative speed. (Hereinafter, the distance direction components of the relative speed and absolute speed of the specific target calculated by the above method are collectively referred to as Doppler speed.)

  Subsequently, the prediction unit 8 predicts the specific target calculated in the previous scan, the observation position of the specific target obtained in the current scan, the amount of change in the Doppler velocity of the specific target for each scan, Based on the estimated position calculation means that calculates the estimated position of the specific target, the estimated speed of the specific target calculated in the previous scan, and the predicted position of the specific target calculated in the previous scan. An estimated speed calculating means for calculating an estimated speed of the specific target based on the moving speed of the specific target to the observation position and the amount of change in the Doppler speed of the specific target for each scan, and the estimated position and From the estimated speed, a predicted position, which is a prediction of the observation position of the specific target obtained in the next scan, is calculated. The specific target is tracked and captured by repeating such processing. In the present embodiment, the most effective implementation method including both the estimated position calculation means and the estimated speed calculation means will be described, but a configuration in which any one of the means and the prior art may be combined may be used. .

  As illustrated in FIG. 4, the prediction unit 8 includes a motion estimation unit 81, an estimation coefficient determination unit 82, and a memory 83.

  The motion estimation unit 81 includes the above-described estimated position calculation means and estimated speed calculation means, and both use digital filters such as an αβ tracker and a Kalman filter so that stable estimation results can be obtained. Specific processing will be described later.

  The estimation coefficient determination unit 82 compares the Doppler velocity of the specific target in the current scan calculated by the phase change information acquisition unit 6 with the Doppler velocity in the previous scan, and uses it for the filter processing in the motion estimation unit 81. Output the coefficient k.

  The memory 83 stores information on the Doppler velocity in the previous scan, which is a target to be compared with the Doppler velocity of the specific target in the current scan, for each scan by the estimation coefficient determination unit 82.

このとき、重み付け係数α"は、α"＝α＋ｋで表わされる。αは従来のαβフィルタの式で表わされる変数である。β"は、α"とβ"の関係式によって求める。もしくは、α"と独立してα"と同様に、β"＝β＋ｋとして求める。なお、β"について、α"とは異なる別の規則で定められた係数ｋ´を用いてもよい。ここで、係数ｋは、位相変化情報取得部が取得したｎ回目のスキャンでのドップラ速度と（ｎ−１）回目のスキャンでのドップラ速度との変化量ΔＶ_ｄｄ（ｎ）_ｒに基づいて決定される変数である。例えば、定数τとして、ｋ＝τ・｜ΔＶ_ｄｄ（ｎ）_ｒ｜のように定める。これによって、ドップラ速度に変化があるときは、ターゲットである特定物標の速度が変化したことを意味し、追従した運動推定を行うためにフィルタの係数をより軽い（α、βを大きくする）ものにし、追従することが可能である。なお、ここでは観測時間毎のドップラ速度の変化量ΔＶ_ｄｄ（ｎ）_ｒとしているが、ｎ回目スキャンのドップラ速度Ｖ_ｄ（ｎ）_ｒと（ｎ−１）回目スキャンの推定速度Ｖ_ｓ（ｎ）_ｒとの差ΔＶ_ｄｓ（ｎ）_ｒとして、同様の処理をしてもよい。 Here, a specific motion estimation method of the motion estimation unit 81 in the present embodiment will be described. FIG. 5 shows a state in which the predicted position of the specific target for the next (n + 1) th scan is obtained from the nth scan of the radar apparatus. Now, assuming that the prediction position in the n-th scan obtained by the prediction unit is X _p (n), the observation position is X _o (n), and the prediction position in the (n + 1) -th scan is X _p (n + 1), A current estimated position X _s (n) is calculated from the n-th predicted position X _p (n) and the observed position X _o (n). Further, the estimated velocity at the (n-1) th scan and _V s (n-1), n th predicted position _X p (n), from the observation position _X o (n), the current estimated speed V _s (n) is calculated. A specific calculation method is represented by the following equation.

At this time, the weighting coefficient α ″ is represented by α ″ = α + k. α is a variable represented by a conventional αβ filter equation. β ″ is obtained by a relational expression between α ″ and β ″. Alternatively, it is obtained as β ″ = β + k, independently of α ″, as in α ″. For β ″, a coefficient k ′ determined by another rule different from α ″ may be used. Here, the coefficient k is determined based on a change amount ΔV _dd (n) _r between the Doppler velocity in the n-th scan acquired by the phase change information acquisition unit and the Doppler velocity in the (n−1) -th scan. Variable. For example, the constant τ is determined as k = τ · | ΔV _dd (n) _r |. As a result, when there is a change in the Doppler velocity, it means that the velocity of the target that is the target has changed, and the filter coefficients are lighter to increase the following motion estimation (increase α and β) It is possible to follow and follow. Note that here, the change amount ΔV _dd (n) _r of the Doppler velocity for each observation time is used, but the Doppler velocity V _d (n) _r of the n-th scan and the estimated velocity V _s (n-1) of the (n−1) -th scan. ) as the difference [Delta] V _{ds (n) r} with _r, it may be a similar process.

から、（ｎ＋１）回目のスキャンでのターゲットである特定物標の予測位置が算出される。 Using the estimated position X _s (n) and V _s (n) calculated in this way,

Thus, the predicted position of the specific target that is the target in the (n + 1) th scan is calculated.

By repeating the above-described processing, it is possible to track and capture a specific target as a target with higher accuracy than in the past.

  As described above, the Doppler speed reflects the instantaneous speed of a specific target by changing the filter coefficient based on the phase change information (Doppler speed) for each scan and calculating the estimated position and estimated speed. Therefore, the tracking error can be further reduced, and the target can be tracked and captured with higher accuracy than in the past.

(Embodiment 2)
In the present embodiment, the configuration excluding the prediction unit and the function / theory of the configuration are the same, and are omitted.
In the prediction unit 8 according to the present embodiment, the Doppler velocity change amount ΔV _dd (n) _r for each observation time and the observation position of the specific target obtained in the current scan from the prediction position of the specific target calculated in the previous scan. The target is tracked / captured by changing the filter coefficient based on the comparison with the moving speed (speed change amount) up to and estimating the movement of the target.

  As illustrated in FIG. 6, the prediction unit 8 includes a motion estimation unit 801, an estimation coefficient determination unit 802, and a memory 803.

  The motion estimation unit 801 includes the aforementioned estimated position calculation means and estimated speed calculation means, and both use digital filters such as an αβ tracker and a Kalman filter so that stable estimation results can be obtained. Specific processing will be described later.

The estimation coefficient determination unit 802 moves from the predicted position of the specific target calculated by the motion estimation unit 801 in the previous scan to the observation position of the specific target obtained by the current scan acquired by the target information acquisition unit (speed). Change amount) and comparing the moving speed with the change amount ΔV _dd (n) _r (ΔV _ds (n) _r ) for each observation time of the Doppler velocity calculated by the phase change information acquisition unit 6, Based on the comparison, the coefficient m used for the filter processing in the motion estimation unit 801 is output.

  The memory 803 stores information on the Doppler speed in the previous scan, which is a target to be compared with the Doppler speed of the specific target in the current scan, for each scan by the estimation coefficient determination unit 802.

  Here, a specific motion estimation method of the motion estimation unit 81 in the present embodiment will be described. FIG. 7 shows a state in which the predicted position of the specific target for the next (n + 1) th scan is obtained from the nth scan of the radar apparatus.

重みづけ係数α'''は、α'''＝α＋ｍであらわされる。αは従来のαβフィルタの式であらわされる変数である。β'''は、αとβの関係式によって求める。もしくは、α'''と独立してα'''と同様に、β'''＝β＋ｍとして求める。なお、β'''について、α'''とは異なる別の規則で定められた係数ｍ´を用いてもよい。ここで、係数ｍは、位相変化情報取得部が取得したｎ回目のスキャンでのドップラ速度と（ｎ−１）回目のスキャンでのドップラ速度との変化量ΔＶ_ｄｄ（ｎ）_ｒと、ｎ回目スキャンでの予測位置から観測位置への移動速度ΔＶ_ｏｐ（ｎ）_ｒとに基づいて決定される変数である。 Now, assuming that the prediction position in the n-th scan obtained by the prediction unit is X _p (n), the observation position is X _o (n), and the prediction position in the (n + 1) -th scan is X _p (n + 1), A current estimated position X _s (n) is calculated from the n-th predicted position X _p (n) and the observed position X _o (n). Further, the estimated velocity at the (n-1) th scan and _V s (n-1), n th predicted position _X p (n), from the observation position _X o (n), the current estimated speed V _s (n) is calculated. A specific calculation method is represented by the following equation.

The weighting coefficient α ′ ″ is expressed as α ′ ″ = α + m. α is a variable expressed by an equation of a conventional αβ filter. β ″ ′ is obtained by a relational expression between α and β. Alternatively, it is obtained as β ′ ″ = β + m independently of α ″ ′ as in α ′ ″. For β ′ ″, a coefficient m ′ defined by another rule different from α ′ ″ may be used. Here, the coefficient m is a change amount ΔV _dd (n) _r between the Doppler velocity in the n-th scan acquired by the phase change information acquisition unit and the (n−1) -th scan, and the n-th time. This is a variable determined based on the moving speed ΔV _op (n) _r from the predicted position to the observation position in the scan.

The predicted position X _p (n) is obtained from the past estimated position and estimated speed, assuming that the target is moving at a constant velocity. Therefore, it is considered that the difference between the predicted position X _p (n) and the observed position X _o (n) represents a position change caused by the deviation from the uniform velocity motion. That is, the time differentiation of the position change can be said to be the speed change amount ΔV _op (n) _r from the previous (n−1) to the current (n).

Here, for example, for ΔV _op (n) _r and ΔV _dd (n) _r , m is increased when the signs are the same, and m = 0 is set when the signs are different. Specifically, for example, m = t · (ΔV _op (n) _r −ΔV _dd (n) _r ) + u, (α ≦ α + m ≦ 1 (or predetermined value), where t is a change rate and u is an offset amount. The upper limit value is 1 or less)). As a result, when there is a change in the Doppler velocity, it means that the velocity of the target that is the target has changed, and the filter coefficients are lighter to increase the following motion estimation (increase α and β) It is possible to follow and follow.

By applying the estimated position X _s (n) and V _s (n) calculated in this way to (Expression 21), the predicted position of the specific target that is the target in the (n + 1) th scan is calculated. The
By repeating the above-described processing, it is possible to track and capture a specific target as a target with higher accuracy than in the past.

In the first embodiment, only by ΔV _{dd (n) r,} because it senses the speed change, if there is an error in ΔV _{dd (n) r} is likely to modifications incorrect. On the other hand, in the present embodiment, since the correction amount is determined from ΔV _op (n) _r and ΔV _dd (n) _r , the possibility of erroneous correction is lower than in the first embodiment.
It should be noted that here, the feed rate change amount ΔV _op (n) _r and the Doppler velocity change amount ΔV _dd (n) _r from the predicted position to the observation position for each observation time are used instead of ΔV _dd (n) _r . The same processing may be performed as a difference ΔV _ds (n) _r between the Doppler velocity V _d (n) _r of the n-th scan and the estimated velocity V _s (n) _r of the (n−1) -th scan.

DESCRIPTION OF SYMBOLS 1 Radar antenna 2 Transmission / reception part 3 A / D conversion part 4 Target information acquisition part 6 Phase change information acquisition part 7 Own ship information acquisition part 8 Prediction part 9 Display part 10 Target motion estimation apparatus 41 Target candidate detection part 42 Target selection Unit 61 sweep memory 62 phase change amount calculation unit 63 speed calculation unit 81 motion estimation unit 82 estimation coefficient determination unit 83 memory 801 motion estimation unit 802 estimation coefficient determination unit 802 memory 101 signal measurement unit 102 motion estimation unit 103 data display unit

Claims (9)

A target motion estimation device that scans a predetermined area by repeatedly transmitting and receiving electromagnetic waves,
An echo signal acquisition unit for acquiring an echo signal obtained by reflecting the transmitted electromagnetic wave on the target;
A phase change information acquisition unit for calculating and acquiring a Doppler velocity of the specific target based on a phase change amount between two or more echo signals from the specific target, the distance from the electromagnetic wave transmission source being substantially the same and different in azimuth; ,
Based on the echo signal acquired by the echo signal acquisition unit, a target information acquisition unit for acquiring the observation position of the specific target;
Using the Doppler velocity and the observation position, a prediction unit that calculates a predicted position that is an expected observation position of the specific target obtained in the next scan,
Equipped with a,
The prediction unit
The estimated speed of the specific target of the previous scan,
The moving speed from the predicted position of the previous scan to the observation position of the current scan,
An estimated speed weighting amount based on a comparison between the Doppler speed of the previous scan or the estimated speed and a change amount of the Doppler speed of the current scan and the moving speed;
To calculate the estimated speed of the current scan,
A target motion estimation apparatus that calculates the predicted position of the next scan using the estimated speed of the current scan, the observation position of the current scan, and the predicted position of the previous scan. The target motion estimation apparatus according to claim 1 ,
The estimated speed weighting amount is determined based on a difference between the change amount and the moving speed. The target motion estimation apparatus according to claim 1 or 2 ,
The estimated speed weighting amount is determined based on a comparison between a sign of the change amount and a sign of the moving speed . The target motion estimation device according to any one of claims 1 to 3,
The prediction unit
The predicted position of the previous scan;
The observation position of the scan this time,
An estimated position weighting amount based on a comparison between the Doppler speed of the previous scan or the estimated speed and the change amount of the Doppler speed of the current scan and the moving speed;
To further calculate the estimated position of the specific target of the current scan,
A target motion estimation apparatus that calculates the predicted position of the next scan using the estimated speed of the current scan and the estimated position of the current scan. The target motion estimation device according to claim 4 ,
The estimated position weighting amount is determined based on a difference between the change amount and the moving speed. The target motion estimation apparatus according to claim 4 , wherein:
The estimated position weighting amount is determined based on a comparison between a sign of the change amount and a sign of the moving speed . The target motion estimation apparatus according to any one of claims 1 to 6,
An antenna for transmitting and receiving the electromagnetic wave;
And a display for displaying surrounding information based on the echo signal. A target motion estimation method that scans a predetermined area by repeatedly transmitting and receiving electromagnetic waves,
An echo signal acquisition process for acquiring an echo signal obtained by reflecting the transmitted electromagnetic wave on the target;
A phase change information acquisition step of calculating and acquiring a Doppler velocity of the specific target based on a phase change amount between two or more echo signals from the specific target, the distance from the electromagnetic wave transmission source being substantially the same and different in azimuth; ,
Based on the echo signal, the target information acquisition process for acquiring the observation position of the specific target,
Using the Doppler velocity and the observation position, a prediction process for calculating a prediction position that is an expected observation position of the specific target obtained in the next scan,
Have
The prediction process is
The estimated speed of the specific target of the previous scan,
The moving speed from the predicted position of the previous scan to the observation position of the current scan,
An estimated speed weighting amount based on a comparison between the Doppler speed of the previous scan or the estimated speed and a change amount of the Doppler speed of the current scan and the moving speed;
To calculate the estimated speed of the current scan,
A target motion estimation method, wherein the predicted position of the next scan is calculated using the estimated speed of the current scan, the observation position of the current scan, and the predicted position of the previous scan.
The target motion estimation method according to claim 8,
The prediction process is
The predicted position of the previous scan;
The observation position of the scan this time,
An estimated position weighting amount based on a comparison between the Doppler speed of the previous scan or the estimated speed and the change amount of the Doppler speed of the current scan and the moving speed;
To further calculate the estimated position of the specific target of the current scan,
A target motion estimation method , wherein the predicted position of the next scan is calculated using the estimated speed of the current scan and the estimated position of the current scan .

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