JPH03148085A - Ship-signal processing method and radar system - Google Patents

Abstract

PURPOSE:To estimate the true movement of a target accurately when own ship performs quick acceleration, deceleration and the like by estimating the true movement of the target based on the relative-movement estimating signal of the target with respect to own ship based on a radar video signal and the smoothed movement signal of own ship. CONSTITUTION:A radar video signal corresponding to the scanning of an antenna 311, a radar trigger signal and an antenna bearing signal are outputted from a radar apparatus. The signals are received, and observation with respect to a target that is captured with respect to the radar video signal is performed with a target observing part 321, and the distance and the bearing of the target are found. The obtained target distance and bearing are sent into an operating part 352 through an I/O interface part 351. A bow bearing signal (k) of own ship from a gyroscope 33 and an own-ship speed signal (l) from a speed log 34 are sent into the processing part 352 through the interface part 351. A CPU 353 performs smoothing processing based on the target distance/bearing signals and the signal received in the past, and the relative movement is estimated. The true movement of the target is obtained based on the obtained smoothed relative movement data and the smoothed own-ship movement data. The movement is converted into the coordinate values and the values are sent into a display-data forming part 322.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to automatic collision prevention assistance system for ships (hereinafter referred to as ARPA).
The present invention relates to a radar system equipped with a ship signal processing method for estimating the true motion of a target and a true motion estimation function in a tracking radar device such as the following.

[Prior Art] In general, tracking radar devices such as ARPA measure the relative position W (distance, direction, etc.), true motion (speed, course, etc.), and relative motion (relative speed, relative course, etc.) of a tracked target. It has the function of

What is directly obtained from the radar video signal are observation signals of distance and direction that represent the relative position from the own ship. First, relative motion is calculated from temporal changes in distance and direction, and then true motion is calculated by adding own ship motion to this relative motion.

At this time, since the observation signal of the target distance and direction obtained from the radar image signal contains errors, smoothing, that is, a type of low-pass filter processing is performed to reduce this error.

[Problems to be Solved by the Invention] However, in this conventional technique, although the observation error is reduced by the low-pass filter, on the contrary,
A delay will occur in response to a sudden change in relative motion.

That is, when the target or own ship suddenly accelerates, decelerates, or changes course, a delay occurs in the relative movement.

As a result, the true motion calculated by adding the own ship's motion to the relative motion will also have errors due to sudden acceleration/deceleration or sudden changes in course of the target or own ship.

In particular, a sudden change in the own ship's motion causes a very large true motion error, which is a problem in ship navigation, as described in 3-4- below.

The present invention has been made to solve these problems, and is capable of accurately estimating the true motion of a tracking target in a tracking radar device such as ARPA, even when the own ship suddenly accelerates, decelerates, or changes course. The objective is to provide a ship signal processing system that enables

Furthermore, another object of the present invention is to be able to accurately estimate the true motion of a target, and based on this, calculate relative motion and CPA.
An object of the present invention is to provide a radar system that can accurately calculate collision prevention data such as (closest approach distance) and TCPA (time to closest point of approach).

[Means for solving the problem] The above purpose is to estimate the relative movement of the target to the own ship based on observation signals regarding the distance and direction of the target obtained from radar image signals, and to generate a signal indicating the movement of the own ship. For,
As a result, the true motion of the target is estimated from the relative motion estimation signal and the smoothed own ship motion signal by performing smoothing through filter processing that has the same filter characteristics as the filter characteristics used in estimating the relative motion. achieved.

That is, according to the present invention, there is provided a relative motion estimating means for estimating the relative movement of a target with respect to the own ship based on observation signals regarding the distance and direction of the target obtained from radar image signals; For the signal, as a result,
Own ship motion smoothing means performs smoothing through filter processing that has the same filter characteristics as the filter characteristics in the relative motion estimation, and estimates the true motion of the target from the relative motion estimation signal and the smoothed own ship motion signal. A ship signal processing method is obtained, which is characterized by comprising a true motion estimating means.

Further, according to the present invention, a radar system having a function of estimating the true motion of a target can be obtained using the above-mentioned ship signal processing method.

Such a radar system includes, for example, a radar device that performs antenna scanning and outputs a radar video signal, and a radar device that observes a target based on signals from the radar device and displays information on the radar device. An observation data processing device that creates data, a means for detecting the heading of the ship, a means for detecting the own ship's speed, and performs calculations regarding the motion of the target based on the observation data of the target, the heading, and the own ship's speed. and an arithmetic processing unit.

The arithmetic processing unit has a function of estimating the relative movement of the target with respect to the own ship based on observation signals regarding the distance and direction of the target obtained from the radar image signal, and a signal indicating the movement of the own ship. As a result, there is a function to perform smoothing through filter processing that has the same filter characteristics as the filter characteristics in the relative motion estimation, and a function to estimate the true motion of the target from the relative motion estimation signal and the smoothed own ship motion signal. A device comprising the following can be obtained.

[Effect] The operation of the present invention will be explained using FIG. 2.

Fig. 2 is a waveform diagram schematically showing a signal waveform to explain the action and effect of the present invention. This is assumed to change in steps.

First, a case not based on the present invention will be described.

When own ship speed changes as shown in Figure 2 (■), the target relative speed changes as shown in Figure 2 (■). On the other hand, the smoothed relative motion signal calculated by the relative motion estimating means based on the observation signal of the target distance and direction obtained from the radar image signal is determined by the smoothing characteristic of the relative motion estimating means, that is, the low-pass filter. Due to its characteristics, it becomes as shown in ■ in the same figure.

Therefore, when the true motion is calculated from the own ship speed signal in Figure 2 ■ and the smoothed relative motion signal in Figure 2 occurs.

Next, according to the present invention, the own ship speed shown in Figure 2 (■) is
As a result, by means of own ship motion smoothing.

A filter process is performed to have the same filter characteristics as the filter characteristics in the relative motion estimating means, and a smoothed own ship speed signal shown in FIG. 2 is output.

The true motion estimating means adds this smoothed own ship speed signal and the smoothed relative speed signal shown in (2) in the figure to calculate the error-free true motion shown in (2) in the same figure.

Further, according to the present invention, even if noise is included in the own ship motion signal output from the gyro compass and speed log, the noise is removed by the filter processing of the own ship motion smoothing means, and as a result, accurate The target true motion can be estimated.

[Example] Next, one embodiment of the present invention will be described using the drawings.

FIG. 1 is a block diagram showing an embodiment for realizing the ship signal processing method of the present invention.

In the figure, 1 is a relative motion estimating means, 2 is an own ship motion smoothing means, and 3 is a true motion estimating means.

Each means will be explained in detail below, but before that, the coordinate system will be explained.

The observation signal of the target position obtained from the radar image signal is the distance and direction from the own ship, and is in a polar coordinate system.

In addition, as own ship motion signals, a heading signal outputted from a gyro compass and an own ship speed signal outputted from a speed log are generally used, and these are also polar coordinate system signals. Furthermore, the true motion of a target is often ultimately expressed in a polar coordinate system of speed and course.

However, in the intermediate calculation process, it is not necessary to use the polar coordinate system, but it is also possible to convert the polar coordinates to X-Y orthogonal coordinates and use the x-y coordinate system.

In this embodiment, a case will be explained in which the target distance/azimuth observation signal and the ship's motion signal are converted into an X-Y coordinate system, and the true motion is also expressed in the X-Y coordinate system.

The relative motion estimating means 1 receives an observation signal of the distance and direction of the target obtained from the radar image signal.

Outputs a smoothed relative motion signal in the x-y coordinate system.

First, the target distance/direction observation signal is converted into a position signal in the x-y coordinate system, and the smooth relative velocity is calculated in the x-y coordinate system. It is sufficient to perform α-β filter processing. The purpose is to calculate a smoothed position with reduced noise from an observed position signal that includes observation noise, and further to calculate a smoothed relative velocity.

A one-dimensional α-β filter is expressed as in equation (1). In equation (1), Xm is the target position observed from the radar video signal, Xs is the target smoothed position, Xp is the predicted target position, Vs is the target smoothed relative velocity, α, β are filter constants, and T is This is the observation interval.

Xs(k) =Xp(k) +α[Xm(k)−X
p(k)]Vs(k) =Vs(k-1)+β[Xm
(k) −Xp(k)]/TXp(k+1)
-Xs(k)+Vs(k) ・T -(1) This α-β filter is a kind of low-pass filter, and α
Alternatively, if the value of β is decreased, the smoothing characteristic of the filter becomes more noticeable, and if the value of α or β is increased, the tracking characteristic of the filter becomes more noticeable. Regarding the frequency characteristics of the α-β filter.

For example, the literature CD, E. Mayiatis
” Comparison of a-β and
Kalman filter in track wh
ilescan radars”].

The own-ship motion smoothing means 2 generates an own-ship motion signal (
own ship speed signal), and performs filtering on it that results in the same filter characteristics as the α-β filter processing in the relative motion estimating means 1,
Outputs smoothed own ship motion signal.

The reason and effect is that, as mentioned above, when calculating the true speed from the relative speed signal output from the relative motion estimating means 1 and the own ship speed signal without filtering, the own ship suddenly accelerates, decelerates, suddenly changes course. Then, α of the relative motion estimating means 1
- Due to the low-pass characteristics of the β filter, a delay occurs in the relative speed signal, causing a large error in the true speed. However, by applying filtering with the same characteristics to the own ship speed signal, the same delay as the relative speed signal is achieved. By having this, errors in true motion are suppressed.

Also, if your ship's speed signal contains noise.

By smoothing the own ship's speed and removing it, it has the effect of being able to accurately estimate the target true speed.

Next, a specific method for performing filtering that has the same filter characteristics as the α-β filter in the relative motion estimating means 1 will be described.

First, consider the transfer function Gvs(Z) when the smooth relative velocity Vs is calculated from the am position Xm of the target by α-β filter processing in the relative motion estimating means 1.

Here, Adj* represents the cofactor matrix of *.

therefore.

(Left below) Then, equation (1) becomes X(k)=AX(k-1)+BX++(k)-(2
)Xp(k+1)=CX(k)−(3
).

The transfer function Gs(Z) in equation (2) is X(k),
l(k) (7) From Z transformation X(Z), Xm(Z), 13
- 14- Gvs (Z) = Gxv (Z)・Gvv' (Z)...
(8) becomes.

Next, consider the own ship speed signal. -Dimension own ship speed signal V[k) is -dimensional own ship position signal X(k), V(k)=(X(k)-X(k-1))/T...
It can be considered that the relationship (6) exists. At this time,
The transfer function Gxv(Z) from X(k) to v(k) is.

Therefore, in order to apply filtering to the ship's speed that has the same characteristics as the α-β filter in the relative motion estimating means 1, the transfer function Gvv' (Z
) can be used as a filter.

(9) Here, the filter applied to own ship speed 1k) is v′(k)
=c1v'0c-1)+c2v'(k-2)+(1-
Cz-C2)V(k)...(10) However, if V'(k) is smoothed-acceleration, then (1
The transfer function avv' (z) of equation 0) is.

Then, from equations (9) and (11), C□=2-α-β C2=-(1-α) (12).

The true motion estimation means 3 estimates the true motion of the target from the smoothed relative motion signal output from the relative motion estimation means 1 and the smoothed own ship motion signal output from the own ship motion smoothing means 2. .

Specifically, the true speed in the X-Y coordinate system is calculated by adding the smoothed ratio phase 5-16 speed signal expressed in the X-Y coordinates and the smoothed own ship speed signal.

The true motion signal of the target obtained by the true motion estimating means 3 may be further smoothed if necessary.

Furthermore, by recalculating the relative motion signal based on the true motion signal obtained through the above procedure, the target relative motion can be accurately estimated even when the own ship suddenly accelerates, decelerates, or changes course.

In this case, the relative motion may be calculated from the true motion signal and the unfiltered own ship motion signal.

Furthermore, collision prevention data such as CPA and TCPA can be calculated accurately, which is very effective for safe navigation of ships.

In addition, in the above embodiment, the calculation of the smoothed relative motion signal in the relative motion estimating means l was performed using an α-β filter, but in addition to this, an α-β-γ filter,
There are various methods such as Kalman filter. Also, α−β
The Vs of the filter may be further smoothed by equalizing the movement rate, or the smoothed relative velocity may be calculated based on the Xs of the α-β filter. It goes without saying that the filter in the own ship motion smoothing means 2 is set according to the relative motion estimating means 1.

Next, an embodiment of a radar system including means for implementing the above-described ship signal processing method will be described with reference to the drawings.

FIG. 3 shows the configuration of an embodiment of the radar system of the present invention.

The radar system of this embodiment includes a radar device 31, an observation data processing device 32 that observes a target based on a signal from the radar device 31, and creates display data for the radar device 31, and an observation data processing device 32 that determines the heading of the ship. A gyro 33 detects the ship's own ship's speed and outputs a heading signal, and a speed log 34 detects the ship's own ship's speed and outputs a own ship's speed signal.In addition to controlling the system, it also uses signals obtained from the above-mentioned parts. and an arithmetic processing device 35 that executes various arithmetic operations based on the information.

The arithmetic processing unit 35 of this embodiment operates as described later, thereby functioning also as the relative motion 17-18 estimation means 1, own ship motion smoothing means 2, and true motion estimation means 3 shown in FIG. .

The radar device 31 includes an antenna 311 that transmits and receives radar radio waves, a transceiver 312 that transmits and receives radar radio waves using the antenna 311, displays radar images, and displays display data from the observation data processing device 32. It has an indicator 313 to Note that the antenna 311
The antenna direction signal is transmitted from the transmitter/receiver 312.
A radar video signal and a radar trigger signal are output.

The observation data processing device 32 includes an arithmetic processing device 35, which will be described later.
a target observation unit 32 that obtains a target range/direction signal indicating the distance and direction of the target based on the radar video signal, radar trigger signal, and antenna direction signal under the control of the target observation unit 32;
1, and a display data creation section 3 that creates display data indicating the state of the target based on the target position signal, target relative motion signal, and/or target true motion signal from the arithmetic processing device 35.
22, and a panel control unit 323 that controls the display data creation unit 322 and the system in response to various instructions from an operator to the system, such as instructions for data to be created, to the display data creation unit 322. ing.

Note that the heading is a value with true north as a reference (0 degrees), and is obtained by correcting it using a gyro signal representing the heading direction of the own ship.

The arithmetic processing unit 35 includes a work/○ interface section 351 that functions as an input/output interface for various signals, and an arithmetic processing section 352 that executes arithmetic processing. The arithmetic processing unit 352 is a central processing unit (hereinafter referred to as CPU).
) 353, and a memory 354 for storing programs, calculation data, etc. of the CPU 353.

The radar system of this embodiment has a function of manually or automatically capturing a target from a radar video signal and tracking the target.

Next, the operation of the radar system of this embodiment will be explained.

The radar device 31 outputs a radar video signal, a radar trigger signal, and an antenna azimuth signal in response to scan=19-0- of the antenna 311. In response to this, the target observation unit 321 performs observation regarding the captured target on the radar video signal to obtain its distance and direction. Note that this observation method is already known, so a description thereof will be omitted here. Furthermore, target acquisition can be performed automatically by an automatic acquisition function (not shown) or manually by an operator using a cursor or the like from the panel control section 323.

In this way, the target distance/azimuth signal obtained for each target is sent to the arithmetic processing section 352 via the I10 interface section 351. Further, the gyro 33 sends the own ship's heading signal, and the speed log 34 sends the own ship speed signal to the arithmetic processing section 352 via the I10 interface section 351.

The arithmetic processing unit 352 performs arithmetic processing on various input signals according to the flowchart shown in FIG.

First, the target distance/azimuth signal and own ship's heading/speed signal are taken in via the I10 interface unit 351 and stored in the memory 354 (step 41.42).

Note that these signals have been converted into digital data before being input to the I10 interface section 351.

For example, the target observation unit 321 converts the input radar video signal from analog to digital, treats it as a digital signal, and outputs a digital target distance/azimuth signal. Similarly, the gyro 33 and speed log 34 have an A/D conversion function and output digital data.

Since the various signals taken in are polar coordinate data, this is converted into a rectangular coordinate system (step 43).

Note that the polar coordinate data may be handled as is.

Next, the CPU 353 performs the smoothing process using the α-β filter described above based on the target distance/azimuth signal and those signals captured in the past, and estimates the relative movement (step 44).

21 22 In other words, the transfer function Gvs(Z
).

Further, the CPU 353 performs smoothing processing on the own ship's heading/velocity signal using a filter, which results in filter characteristics similar to those obtained through α-β filter processing, as described above (step 45). That is, the above (
8) Perform filter processing with a transfer function Gvv' (Z) that satisfies the equation.

The CPU 353 determines the true motion of the target based on the smoothed relative motion data and the smoothed own ship motion data obtained in this way (step 46).

Then, the CPU 353 converts the coordinates of the smoothed relative motion data, smoothed own ship motion data, and true motion data from the orthogonal coordinate system to the polar coordinate system, and displays this via the ■/○ interface section 351. The data is sent to the data creation section 322 (step 47).

The CPU 353 performs such processing for each target and outputs the data. The display data creation unit 322
Upon receiving this, display data is created for the motion signal 1, for example, the true motion signal, instructed by the panel control unit 323. The created display data is sent to the indicator 313 of the radar device 31 and displayed.

Note that when the instruction at the panel control unit 323 changes, the creation of display data for other signals, for example, the target relative motion signal, is stopped. This instruction can be given by the operator by operating a switch or the like on the panel.

In this way, the radar system of this embodiment performs relative motion estimation by smoothing it using the α-β filter, and also estimates the own ship's motion with the same filter characteristics as the α-β filter processing, i.e. , smoothing is performed using a filter with filter characteristics that provide the same delay. Therefore, when estimating true motion using relative motion data and own ship motion data, errors due to filter processing are prevented from occurring.

The radar system described above is an example, and the present invention is not limited to this, and can also be applied to radars with other configurations.

[Effects of the Invention] As explained above, according to the present invention, own ship can suddenly accelerate or decelerate,
Even in the event of a sudden course change, it is possible to accurately estimate the target's true motion, which greatly contributes to the safety of ship navigation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment for realizing the ship signal processing method of the present invention, FIG. 2 is a waveform diagram showing the operation of the ship signal processing method of the present invention, and FIG. 3 is a block diagram showing the configuration of an embodiment of the ship signal processing method of the present invention. FIG. 4 is a block diagram showing the configuration of an embodiment of the radar system, and FIG. 4 is a flowchart showing the operation of the arithmetic processing unit in the above embodiment. DESCRIPTION OF SYMBOLS 1... Relative motion estimation means, 2... Own ship motion smoothing means, 3... True motion estimation means, 31... Radar device,
32... Observation data processing device, 33... Gyro,
34... Speed log, 35... Arithmetic processing unit.

Claims (1)

[Claims] 1. Estimating the relative movement of the target with respect to the own ship based on observation signals regarding the distance and direction of the target obtained from radar video signals, and calculating the result with respect to the signal indicating the movement of the own ship. The method is characterized in that the true motion of the target is estimated from the relative motion estimation signal and the smoothed target motion signal by performing smoothing by a filter process that has the same filter characteristics as the filter characteristic in the estimation of the relative motion. Ship signal processing method. 2. Relative motion estimating means for estimating the relative motion of the target to its own ship based on observation signals regarding the distance and direction of the target obtained from radar image signals; Then, the own ship motion smoothing stage performs smoothing by filtering with the same filter characteristics as the filter characteristics used in estimating the relative motion, and the target truth is calculated from the relative motion estimation signal and the smoothed own ship motion signal. A ship signal processing device comprising true motion estimating means for estimating motion. 3. A radar system having a function of estimating the true motion of a target using the ship signal processing device according to claim 2. 4. A radar device that performs an antenna scan and outputs a radar image signal; an observation data processing device that observes a target based on the signal from the radar device and creates display data for the radar device; and a bow a means for detecting the heading, a means for detecting the own ship's speed, and based on the observation data of the target, the heading and the own ship's speed,
an arithmetic processing unit that executes calculations regarding the movement of the target, the arithmetic processing unit estimating the relative movement of the target with respect to its own ship based on observation signals regarding the distance and direction of the target obtained from the radar image signal. A function to smooth the signal indicating the movement of own ship through filter processing that results in the same filter characteristics as the filter characteristics in the relative movement estimation, and A radar system characterized by having a function of estimating the true motion of a target from own ship motion signals.