JP4026124B2 - Tracking target signal processing method and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tracking target signal processing method, and more particularly to a tracking processing method for a low-speed moving target.
[0002]
[Prior art]
When tracking a moving target with a radar device, etc., a predicted position is calculated from the past plot data of the target, and correlation processing is performed to determine whether the plot data detected at the current time is the same as the target being tracked. When there is a correlation, a method for calculating an estimated position and an estimated speed from target past data and current time plot data is disclosed in, for example, Japanese Patent Laid-Open No. 6-347541.
[0003]
FIG. 4 shows an example of a conventional tracking processing method, in which a gate correlation determination process 2 for determining whether or not the plot 1 obtained at the current time belongs to the tracking target, a current tracking target position, A smoothing process 10 for estimating the speed and a tracking target information recording means 11 for recording the latest tracking target position and speed obtained by the smoothing process are included.
[0004]
In the tracking processing method shown in FIG. 4, when plot 1 is input, target information being tracked is read from tracking target information recording means 11 and input to gate correlation determination processing 2 together with plot 1. In the gate correlation determination process 2, as shown in FIG. 5, the predicted position 12 of the tracking target at the plot detection time is obtained, and the correlation gates 13 to 15 are set around this predicted position.
[0005]
As the size of the correlation gate, a plurality of gate sizes are set in consideration of the detection position error of the plot, the target acceleration, and the like. Plots that have entered these correlation gates are determined as plots of the tracking target. When a plurality of plots enter the correlation gate, the determination is made based on conditions such as selecting the one closest to the predicted position of the tracking target among them. Further, TQ (Tracking Quality), which is a parameter indicating the reliability of the predicted position 12 of the tracking target, is increased or decreased according to the size of the correlation gate where the correlated plot exists.
[0006]
For example, as shown in FIG. 6, when the tracking trajectory 16 of the tracking target is performing acceleration motion, the tracking target moves away from the predicted position 12 of the tracking target predicted on the assumption of constant-velocity linear motion. That is, when a plot is detected at a location away from the predicted position, the reliability of the predicted position is low because the target may be performing an acceleration motion. That is, the value of TQ serves as a standard for determining whether or not the target is performing an acceleration motion.
[0007]
As means for automatically adjusting the reliability of the predicted position, TQ is decreased by 1 when the largest large gate 17 among the plurality of correlation gates is used for correlation. When correlated with the second largest medium gate 18, the TQ maintains its current value. If there is a correlation at the smallest small gate 19, it is determined that the target is moving straight at a constant speed, and TQ is incremented by one. In the case of FIG. 6, since the large gate 17 correlates with the plot 20, TQ is subtracted by 1.
[0008]
When the correlated plot and TQ are determined, the position of the tracking target is estimated by the smoothing process 10 using the position of the plot and the predicted position of the tracking target. As the smoothing method, an αβ filter with a light processing load is often used, and weighting is performed between the correlation plot position 20 and the tracking target predicted position 12 as shown in FIG. 22 is determined.
[0009]
This weighting is determined based on the TQ obtained in the gate correlation determination 2. If TQ is a large value, it indicates that the predicted position of the tracking target is reliable. Therefore, smoothing with more importance on the predicted position is performed, and the smoothed position 21 and the smoothing speed as shown in FIG. 22 is obtained. On the other hand, if TQ is a small value, it indicates that the predicted position 12 of the tracking target is not reliable, and therefore, smoothing with more importance on the correlation plot position is performed, and the smoothed position as shown in FIG. 21 and a smoothing speed 22 are obtained.
[0010]
The obtained smoothing position 21 and smoothing speed 22 are recorded in the tracking target information recording means 11 and read out from the gate correlation determination processing 2 when the plot 1 is input next, and the tracking target predicted position 12 is read. Used for calculation.
[0011]
The error in the detection position of the plot affects the smoothing position and the smoothing speed, and as a result, affects the accuracy of the tracking target predicted position at the next plot detection time. When the error in the smoothing position and the smoothing speed becomes large, in the case of a system that outputs the result as the current tracking target position to the outside, information with a large error is output. Further, when the error in the predicted position of the tracking target becomes large, there is a possibility that the target tracking cannot be continued because it is not correlated with the plot to be correlated.
[0012]
FIG. 8 shows the difference in the influence of the tracking target speed on the smoothing speed when the same error is included in the plot detection position. (A) is the case of a target moving at high speed, and (b) is the case of a target moving at low speed. In these examples, as an example, a case is shown in which weighting is performed such that the midpoint between the tracking target predicted position 12 and the correlation plot position 20 is the smoothed position 25. Furthermore, the direction from the previous smoothing position 23 to the current smoothing position 25 is the current smoothing speed.
[0013]
As can be seen from a comparison between (a) and (b), even if the error in the plot detection position is the same and the smoothing position is the same, the smoothing speed error is not the same. That is, when the speed is slow and the movement amount 27 of (b) is smaller than the movement amount 24 of (a), the smoothing speed 28 of (b) is more correlated than the smoothing speed 26 of (a). The position 20 is greatly affected. Therefore, in the case of a low-speed moving target, the smoothing speed is easily affected by the random error included in the plot detection position, and as a result, the error of the next tracking target predicted position becomes large and the tracking becomes unstable.
[0014]
[Problems to be solved by the invention]
Thus, when tracking processing is performed on a target moving at a low speed and the current position and speed of the target are estimated, the error of the obtained position and speed becomes large, and as a result, it is difficult to continue tracking. There was a problem.
[0015]
In order to reduce the error in the position and speed of the low-speed moving target, a method of adjusting the weighting in the smoothing process so that it is less affected by the error in the plot position can be considered. There arises a problem that the followability to a change in speed and a change in traveling direction is deteriorated.
[0016]
An object of the present invention is to provide a system capable of outputting more accurate tracking target position and speed information and continuing the tracking of the target regardless of the speed of the tracking target.
[0017]
[Means for Solving the Problems]
According to the tracking processing method of the present invention, in a tracking process for estimating the position of the current tracking target and predicting the future position from the plot of the tracking target target (time and position information at that time) obtained with the passage of time, a predetermined processing is performed. A time width is set, and plots detected during the time width are averaged and treated as a single plot (9 in FIG. 1).
[0018]
Further, it has a process (6 in FIG. 1) for determining an optimum time width for averaging the plot based on the moving speed of the tracking target, the motion state, the detection rate of the plot, and the like.
[0019]
Furthermore, in order to determine whether or not to perform plot averaging processing, determination based on the reliability TQ of the tracking target predicted position (3 in FIG. 1), determination based on the tracking target speed (4 in FIG. 1), tracking It is characterized by having a judgment (5 in FIG. 1) based on the uncorrelated duration with the target plot.
[0020]
According to the present invention, by averaging the plots detected during the set time width, the random error included in the plot position information is canceled, and the position error included in the plot after the averaging process is Reduced.
[0021]
In addition, by performing the smoothing process using the plot in which the position error is reduced, the error in the smoothing position and the smoothing speed of the tracking target can be reduced, and the predicted position error of the target can also be reduced. Continuity can be improved.
[0022]
By performing the averaging process, the random error of the plot detection position is reduced, and the original tracking target position information is also averaged. Therefore, if the averaging process is performed by setting a long time width for a target moving at high speed, the detected position error can be reduced, but the position error due to averaging becomes large. Therefore, it is necessary to perform an optimum time width setting process according to the speed of the tracking target to prevent an error due to averaging.
[0023]
Further, when the target is performing an acceleration motion, an error similar to the above is generated. Therefore, an optimum time width setting process corresponding to the target acceleration is performed to prevent an error due to averaging.
[0024]
Furthermore, for tracking targets that move at higher speeds or higher accelerations, the smoothing position and smoothing speed errors will be reduced if the averaging process is not performed, so the averaging process will be performed based on the tracking target speed and acceleration. The necessity determination process is performed to eliminate the influence of the averaging process.
[0025]
Similarly, for tracking targets that do not correlate with the fixed time plot, the current speed and direction of travel cannot be estimated correctly, and performing averaging processing may increase the error in the smoothing position and smoothing speed. is there. Therefore, the necessity of the averaging process is determined based on the plot detection status, and the influence of the averaging process is eliminated.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an embodiment of a tracking target signal processing system of the present invention.
[0027]
The tracking target signal processing method of the present embodiment is based on the plot 1 inputted from the outside and the gate correlation determination processing means 2 that performs correlation determination from the tracking target predicted position, and whether or not the TQ of the tracking target is a certain value or more. A tracking target TQ determining means 3 for determining, a tracking target speed determining means 4 for determining whether or not the tracking target is moving at a certain speed or more, and determining whether or not the tracking target is correlated with the fixed time plot. Tracking target non-correlation determining means 5, averaging time width calculation processing means 6 for calculating a time width required for plot averaging processing, and plot storage means for storing a plot during the calculated required time width 7, an accumulation time determining means 8 for determining whether the plot has been accumulated for a predetermined time, an averaging processing means 9 for averaging the accumulated plots, a current plot from the correlated plot and the predicted position of the tracking target. And smoothing processing means 10 for estimating the position of the target, and a tracking target information recording means 11 for recording the latest tracking target information obtained.
[0028]
Next, the operation of this embodiment will be described in detail with reference to FIG.
[0029]
First, when plot 1 is input from the outside to the tracking processing device, tracking target information is read from tracking target information recording means 11 and input to gate correlation determination processing means 2 together with plot 1. The gate correlation determination processing means 2 performs the same processing as in the conventional technique, selects a tracking target plot, and obtains the tracking target TQ. The selected plot, tracking target information, and TQ are output to the tracking target TQ determination means 3. Also, the tracking target speed input from the TQ and tracking target information recording means 11 is also output to the averaging time width calculation processing means 6.
[0030]
Next, the tracking target TQ determination means 3 determines the TQ value, and if the TQ is equal to or less than a certain value, the target may be accelerating, so the plot position averaging process is not performed and the smoothing process is performed. If the TQ is equal to or greater than a certain value, the tracking target speed determination 4 is performed. The TQ value serving as a determination criterion is determined in consideration of the assumed target motion, the angle measurement error included in the plot, the plot detection status, and the like.
[0031]
As a result of performing tracking target speed determination 4 when TQ is equal to or greater than a certain value, if the speed of the tracking target is equal to or greater than a certain speed, the process proceeds to smoothing processing 10; Do. The speed Vj, which is a determination reference for the tracking target speed determination, is calculated by the following equation using, for example, the plot input time interval Td, the plot angle measurement error Er, and the plot detection rate Pd.
[0032]
_{Vj = ((K 1 * Er} ) (K 2 * Pd)) / (K 3 * Td)
Here, K _{1 to} K ₃ are adjustment coefficients for optimizing Vj from the predicted target motion and the like.
[0033]
If the tracking target is below a certain speed, the tracking target decorrelation determination 5 is performed. If there is no correlation with the plot for a certain time or longer, the process proceeds to the smoothing process 10, and if there is a correlation within a certain time, the averaging time width The process proceeds to calculation process 6. The non-correlation time Tn, which is a determination criterion for tracking non-correlation determination, is calculated by the following equation using, for example, the plot input time interval Td, the plot detection rate Pd, and the tracking target speed Vt.
[0034]
Tn = (K ₄ * Pd) / ( (K ₅ * Td) (K ₆ * Vt) )
Here, K _{4 to} K ₆ are adjustment coefficients for optimizing Tn from the predicted target motion and the like.
[0035]
In the averaging time width calculation processing means 6, for example, the optimum averaging time width Tw is calculated from the following equation using the tracking target TQ, speed Vt, non-correlated duration Ta, plot angle measurement error Er, and plot detection rate Pd. Calculated by
[0036]
_{Tw = ((K 7 * TQ} ) (K 8 * Er)) / ((K 9 * Vt) (K 10 * Ta) (K 11 * Pd))
Here, K _{7 to} K ₁₁ are adjustment coefficients for optimizing Tw based on the predicted movement of the tracking target.
[0037]
When the averaging time width is calculated, a plot correlated with the tracking target is recorded by the plot accumulating means 7 during that period, and an accumulating time determination 8 is performed to determine whether or not it has been accumulated for a predetermined time. When a predetermined time plot is accumulated, the averaging processing means 9 calculates an average value for the position information of the plot.
[0038]
In the smoothing processing means 10, the tracking target information and the plot position information are input, and the smoothing position and the smoothing speed are calculated by the same processing as in the conventional technique. The obtained smoothing position and smoothing speed are recorded in the tracking target information recording means 11.
[0039]
FIG. 2 shows an example in the present embodiment in which a predetermined time width is set, and plots detected during the time width are averaged and handled as one plot. In this example, the four correlation plots 20 detected during the set time width are averaged by the averaging processing means 9 to calculate an averaged correlation plot position 30, and the smoothing processing means 10 The smoothing position 25 and the smoothing speed 29 are calculated from the averaged correlation plot position 30, and the influence of random errors included in the correlation plot position information is reduced.
[0040]
FIG. 3 shows a processing method using a sliding window as a process for calculating the smoothing speed of the low-speed moving target in the present embodiment. This processing method averages past plot data that falls within a predetermined time interval each time a plot is input, and performs position estimation by smoothing processing. Smoothing is performed each time a plot is input. The target position estimation data subjected to the conversion processing can be obtained.
[0041]
In particular, when the target motion changes greatly, it is necessary to output information sequentially, but according to this processing method, target position estimation data is obtained each time a plot is input, and the tracking target Compared with the case where the position estimation is performed every predetermined time width, the time interval for performing the target position estimation can be shortened, so that the latest information can be output as the target position estimation data, and the target tracking can be performed. Accuracy can be improved.
[0042]
【The invention's effect】
The first effect is that an error included in the estimated value of the current tracking target position and speed obtained as a result of the tracking process can be reduced for a target moving at a low speed. This is because the random error included in the position information is canceled by averaging the position information of the plots accumulated for a certain period of time.
[0043]
The second effect is that even if the plot position information is averaged, an increase in the error of the estimated tracking target position and speed is prevented in the target tracking in which the high-speed moving target and the high-acceleration motion are performed. It is possible to prevent the deterioration of the followability with respect to the change. The reason is that there is a means to calculate the optimal plot averaging time width according to the target speed and acceleration, and smoothing processing without performing plot position averaging processing according to the speed and acceleration. This is because it has a determination process for performing the above.
[0044]
The third effect is that the error in the estimated position and speed of the low-speed target can be reduced without placing importance on the tracking target predicted position in the smoothing process. The reason is that the random error included in the position information is canceled by the plot position averaging process, and the position accuracy of the plot input to the smoothing process is improved. This is because the accuracy of the estimated position and speed is improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram illustrating a method for calculating a smoothing speed of a low-speed movement target in the present embodiment.
FIG. 3 is a diagram showing another method for calculating a smoothing speed of a low-speed movement target in the present embodiment.
FIG. 4 is a diagram illustrating an example of a conventional tracking process.
FIG. 5 is a diagram illustrating an example of a gate correlation determination process.
FIG. 6 is a diagram illustrating an example of gate correlation determination for a tracking target performing acceleration motion.
FIG. 7 is a diagram illustrating a difference in smoothing processing result due to a difference in TQ.
FIG. 8 is a diagram illustrating a difference in influence of a correlation plot position on a smoothing speed due to a difference in target speed.
[Explanation of symbols]
1 Plot 2 Gate correlation determination processing 3 Tracking target TQ determination 4 Tracking target speed determination 5 Tracking target non-correlation determination 6 Averaging time width calculation processing 7 Plot accumulation means 8 Accumulation time determination 9 Averaging processing 10 Smoothing processing 11 Tracking target information Recording means 12 Tracking target predicted position 13 to 15 Correlation gate 16 Tracking target movement locus 17 Large gate 18 Medium gate 19 Small gate 20 Correlation plot position 21 Smoothing position 22 Smoothing speed 23 Previous smoothing position 24 Movement Amount (when moving speed is fast)
25 Smoothing position 26 Smoothing speed 27 Movement amount (when moving speed is slow)
28 Smoothing speed 29 Smoothing speed 30 Smoothing correlation plot position 31 Movement amount within set time width (when movement speed is slow)

Claims (6)

The position and speed of the current tracking target are estimated from the correlation plot (time and position information at that time) of the tracking target target being tracked by the device that tracks the moving target , and from the estimated current position and speed of the tracking target. In a tracking process for predicting a tracking target position at the next plot detection time and setting a correlation gate for obtaining the correlation plot at the next plot detection time around the predicted tracking target position, the tracking target position TQ (tracking Quality) is below a predetermined value, or the speed of the tracking target is constant speed or more, or the when decorrelation time of the tracking target is more than a predetermined time, said current tracking in correlation plot alone for each of the correlation plot executes processing to estimate the position and velocity of the target, the tracking target of TQ (tracking Quality) is a predetermined value or more, and speed of the tracking target is constant speed When the non-correlation time of the tracking target is less than or equal to a predetermined time, a predetermined time width is set, and a plurality of correlation plots detected during the time width are averaged to obtain one averaged correlation plot. A tracking target signal processing method comprising: calculating and executing a process of estimating the position and speed of the current tracking target using the calculated averaged correlation plot. The averaged correlation plot is calculated by averaging past correlation plots that fall within the predetermined time interval each time the correlation plot is input, and is calculated each time the correlation plot is input. The tracking target signal processing method according to claim 1, wherein the position and speed of the current tracking target are estimated using an averaged correlation plot. From the tracking target TQ, velocity Vt, non-correlated duration Ta, plotting angle error Er, and plot detection rate Pd,
Tw = ((K ₇ * TQ) (K ₈ * Er)) / ((K ₉ * Vt) (K ₁₀ * Ta) (K ₁₁ * Pd))
Here, K _{7 to} K ₁₁ are adjustment coefficients for optimizing Tw by the motion of the tracking target to be predicted.
3. The tracking target signal processing method according to claim 1, wherein the averaging time width Tw calculated by the step is used as the predetermined time width. The position and speed of the current tracking target are estimated from the correlation plot (time and position information at that time) of the tracking target target being tracked by the device that tracks the moving target , and from the estimated current position and speed of the tracking target. In the tracking target signal processing method for predicting the tracking target position at the next plot detection time, and setting the correlation gate for obtaining the correlation plot at the next plot detection time around the predicted tracking target position ,
First tracking target signal processing means for estimating a current tracking target position and velocity for each correlation plot;
A time width setting means for setting a predetermined time width; a plot storage means for storing the plurality of correlation plots detected during the predetermined time width; and averaging the plurality of stored correlation plots. Second tracking target signal processing means having averaging processing means for calculating one averaged correlation plot, and smoothing processing means for estimating the position and velocity of the current tracking target based on the calculated averaged correlation plot When,
When the tracking target TQ (Tracking Quality) is below a certain value, the tracking target speed is above a certain speed, or the non-correlation time of the tracking target is above a certain time, the first tracking target signal processing means is When the tracking target TQ (Tracking Quality) is not less than a certain value, the tracking target speed is not more than a certain speed, and the non-correlation time of the tracking target is not more than a certain time, the second tracking target signal is selected. Tracking target signal processing selection means for selecting processing means;
A tracking target signal processing system characterized by comprising: The averaging processing means inputs a past correlation plot that falls within the predetermined time width from the plot storage means every time the correlation plot is input, averages it, and outputs an averaged correlation plot, 5. The tracking target signal processing according to claim 4, wherein the smoothing processing unit inputs the averaged correlation plot each time the correlation plot is input, and estimates a current tracking target position and velocity. method. The time width setting means calculates the following equation from the tracking target TQ, velocity Vt, uncorrelated duration Ta, plot angle measurement error Er, and plot detection rate Pd:
Tw = ((K ₇ * TQ) (K ₈ * Er)) / ((K ₉ * Vt) (K ₁₀ * Ta) (K ₁₁ * Pd))
Here, K _{7 to} K ₁₁ are adjustment coefficients for optimizing Tw by the motion of the tracking target to be predicted.
6. The tracking target signal processing method according to claim 4, further comprising a function of setting the averaging time width Tw calculated by the step as the predetermined time width.

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