JP7596155B2 - Radar target tracking device and radar target tracking program - Google Patents

Description

This disclosure relates to technology for tracking multiple radar targets.

Technology for detecting new targets in addition to already tracked targets using gate processing is disclosed in Patent Document 1 and other publications. A specific example of gate processing in the prior art is shown in Figure 1.

In the left column of FIG. 1, the radar system R detects a radar target T1. The observation position of the radar target T1 is indicated by a black circle, and the observed Doppler velocity of the radar target T1 is v _o <0 (the direction approaching the radar system R). A gate G1 is set around the observation position of the radar target T1, and the gate width is set wider for the same direction with respect to the observed Doppler velocity of the radar target T1 than for the opposite direction. The radar system R detects a tracked target T2. The predicted position of the tracked target T2 is indicated by a white circle (inside the gate G1), and the predicted Doppler velocity of the tracked target T2 is v _p . If |v _o -v _p |≦v _c (v _c is the threshold Doppler velocity difference) is satisfied, the radar target T1 is determined to be the same target as the tracked target T2.

In the right column of FIG. 1, the radar system R detects a radar object T3. The observation position of the radar object T3 is indicated by a black circle, and the observed Doppler velocity of the radar object T3 is v _o >0 (a direction moving away from the radar system R). The gate G3 is set around the observation position of the radar object T3, and the gate width is set wider for the same direction with respect to the observed Doppler velocity of the radar object T3 than for the opposite direction. The radar system R detects a tracked object T4. The predicted position of the tracked object T4 is indicated by a white circle (inside the gate G3), and the predicted Doppler velocity of the tracked object T4 is v _p . If |v _o -v _p |>v _c (v _c is a threshold Doppler velocity difference) is satisfied, the radar object T3 is determined to be a new object different from the tracked object T4.

JP 2002-156449 A

The technology for tracking not just one target but multiple targets using gate processing can be considered as shown below. A specific example of gate processing to be solved is shown in Figure 2.

In the left column of FIG. 2, the radar system R detects the tracked objects T5 and T6. The predicted position of the tracked object T5 is shown by a black circle, and the observed position of the tracked object T5 is shown by a black square. Gate G5 is set around the predicted position of the tracked object T5. The predicted position of the tracked object T6 is shown by a white circle, and the observed position of the tracked object T6 is shown by a white square. Gate G6 is set around the predicted position of the tracked object T6. The predicted positions of the tracked objects T5 and T6 are not very close to each other, gates G5 and G6 do not overlap each other, the observed position of the tracked object T5 exists only inside gate G5, and the observed position of the tracked object T6 exists only inside gate G6. Therefore, the predicted position of the already tracked target T5 can be correctly linked to the observed position of the already tracked target T5. And, the predicted position of the already tracked target T6 can be correctly linked to the observed position of the already tracked target T6.

In the right column of FIG. 2, the radar system R detects the tracked objects T7 and T8. The predicted position of the tracked object T7 is shown by a black circle, and the observed position of the tracked object T7 is shown by a black square. Gate G7 is set around the predicted position of the tracked object T7. The predicted position of the tracked object T8 is shown by a white circle, and the observed position of the tracked object T8 is shown by a white square. Gate G8 is set around the predicted position of the tracked object T8. The predicted positions of the tracked objects T7 and T8 are quite close to each other, and gates G7 and G8 overlap each other, with the observed position of the tracked object T7 existing inside gates G7 and G8, and the observed position of the tracked object T8 existing inside gates G7 and G8. Therefore, it is possible that the predicted position of the already tracked target T7 and the observed position of the already tracked target T8 are erroneously linked. It is also possible that the predicted position of the already tracked target T8 and the observed position of the already tracked target T7 are erroneously linked.

Therefore, in order to solve the above problem, the present disclosure aims to track multiple radar targets with high accuracy by correctly linking the predicted position and observed position of each radar target, even when the multiple radar targets are close to each other.

To solve the above problem, when the observed positions of multiple radar targets exist within a position gate set around the predicted position of a single radar target, the radar target having the observed Doppler velocity closest to the Doppler component of the predicted velocity of the single radar target is selected, and the predicted position of the single radar target is linked to the observed position of the selected radar target.

Specifically, the present disclosure is a radar target tracking device that includes a target tracking unit that calculates a current smoothed position of the radar target based on the current predicted position and observed position of the radar target, calculates a current smoothed velocity of the radar target based on the current predicted position, observed position, and predicted velocity of the radar target, calculates a next predicted position of the radar target based on the current smoothed position and smoothed velocity of the radar target, and calculates a next predicted velocity of the radar target based on the current smoothed velocity of the radar target; and a gate processing unit that, when current observed positions of multiple radar targets exist within a position gate set around the current predicted position of one of the radar targets, selects the radar target having a current observed Doppler velocity closest to the Doppler component of the current predicted velocity of the one of the radar targets, and links the current predicted position of the one of the radar targets with the current observed position of the selected radar target and outputs them to the target tracking unit.

The present disclosure also relates to a radar target tracking program for causing a computer to execute a target tracking step of calculating a current smoothed position of the radar target based on the current predicted position and observed position of the radar target, calculating a current smoothed velocity of the radar target based on the current predicted position, observed position and predicted velocity of the radar target, calculating a next predicted position of the radar target based on the current smoothed position and smoothed velocity of the radar target, and calculating a next predicted velocity of the radar target based on the current smoothed velocity of the radar target; and a gate processing step of selecting the radar target having a current observed Doppler velocity closest to the Doppler component of the current predicted velocity of the one radar target when there are current observed positions of multiple radar targets within a position gate set around the current predicted position of the one radar target, and linking the current predicted position of the one radar target with the current observed position of the selected radar target and outputting them to the target tracking step.

With these configurations, even when multiple radar targets are close to each other, the system can track multiple radar targets with high accuracy by using the Doppler velocity information of each radar target and correctly linking the predicted position and observed position of each radar target.

The present disclosure also provides a radar target tracking device, characterized in that the gate processing unit sets the width of the position gate wider for the same direction relative to the current predicted speed of the one radar target compared to the opposite direction.

This configuration reliably links the observation position of each radar target in the same direction as the predicted speed of each radar target, reliably reduces the probability of picking up noise in the opposite direction to the predicted speed of each radar target, and suppresses the area of the position gate. Furthermore, the predicted speed of each radar target is in any direction across 360° as seen from the radar, and the direction in which the position gate is narrowed is not limited to two directions.

The present disclosure also provides a radar target tracking device, characterized in that the gate processing unit selects the radar target having the current observed Doppler speed within a speed gate set around the Doppler component of the current predicted speed of the one radar target as the one of the multiple radar targets.

With this configuration, even when multiple radar targets are close to each other, it is possible to track multiple radar targets with high accuracy by setting not only a position gate but also a speed gate for each radar target and correctly linking the predicted position and observed position of each radar target.

The present disclosure also provides a radar target tracking device, characterized in that the gate processing unit sets the width of the speed gate wider for an observation signal point cluster of the radar target as the variance value of the currently observed Doppler speed increases.

With this configuration, even when each radar target suddenly changes speed, it is possible to prevent the observed Doppler speed of each radar target from falling outside the respective speed gates, and to prevent each radar target from being determined to be a new target that has suddenly appeared.

The present disclosure also provides a radar target tracking device, characterized in that the gate processing unit sets the width of the speed gate wider for the current predicted speed of the one radar target in the same direction than in the opposite direction.

With this configuration, the observed Doppler speed of each radar target can be reliably linked in the same direction as the predicted speed of each radar target, and the probability of picking up noise in the opposite direction to the predicted speed of each radar target can be reliably reduced, thereby suppressing the volume of the speed gate. Furthermore, the predicted speed of each radar target is in any direction across 360° as seen from the radar, and the direction in which the speed gate is narrowed is not limited to two directions.

In this way, the present disclosure allows multiple radar targets to be tracked with high accuracy, even when the multiple radar targets are close to each other, by correctly linking the predicted position and observed position of each radar target.

FIG. 1 is a diagram showing a specific example of gate processing in the prior art; FIG. 1 is a diagram showing a specific example of gate processing to be solved. FIG. 1 is a diagram illustrating a configuration of a radar system according to the present disclosure. FIG. 2 is a diagram showing a specific example of the target tracking process of the present disclosure. FIG. 2 is a diagram showing a procedure of a first gate processing according to the present disclosure. FIG. 1 is a diagram showing a specific example of a first gate process according to the present disclosure. FIG. 1 is a diagram showing a specific example of a first gate process according to the present disclosure. FIG. 1 is a diagram showing a specific example of a first gate process according to the present disclosure. FIG. 13 is a diagram showing a specific example of a position gate setting according to the present disclosure. FIG. 11 is a diagram showing a procedure of a second gate processing according to the present disclosure. FIG. 13 is a diagram showing a specific example of a second gate process according to the present disclosure. FIG. 13 is a diagram showing a specific example of a speed gate setting according to the present disclosure. FIG. 13 is a diagram showing a specific example of a speed gate setting according to the present disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementations of the present disclosure, and the present disclosure is not limited to the following embodiments.

(Overview of the radar system of the present disclosure)
The configuration of the radar system of the present disclosure is shown in Fig. 3. The radar system R includes a radar transmitting/receiving device 1, a radar target observation device 2, and a radar target tracking device 3. The radar target observation device 2 includes a signal processing unit 21, a signal point extraction unit 22, a clustering unit 23, and a representative point extraction unit 24. The radar target tracking device 3 includes a gate processing unit 31 and a target tracking unit 32, and is a computer on which the radar target tracking program shown in Fig. 5 or 10 is installed.

The radar transceiver 1 irradiates a radar transmission signal to a radar target T and receives a radar reflection signal from the radar target T. The signal processing unit 21 processes the radar reflection signal for each distance bin, each azimuth sector, and each Doppler velocity bin. The signal point extraction unit 22 extracts signal points from the radar reflection signal based on intensity threshold processing. The clustering unit 23 extracts clusters from the extracted signal points based on a signal point density determination. The representative point extraction unit 24 extracts representative points from the extracted clusters based on the density and intensity of the signal points, and calculates the observed position and observed Doppler velocity of the radar target T.

A specific example of the target tracking process of the present disclosure is shown in FIG. 4. The target tracking unit 32 calculates the current smoothed position x _sk of the radar target T based on the current predicted position x _pk and observed position x _ok of the radar target T. Then, the current smoothed velocity v sk of the radar target T is calculated based on the current predicted position x _{pk ,} observed position x _ok , and predicted velocity v pk of the radar target T. Furthermore, the current smoothed acceleration a _sk of the radar target T is calculated based on the current predicted position x _pk , observed position x _ok , and predicted acceleration _{a pk} of the radar target T. In the αβγ filter, calculation is performed as shown in Equation 1, where α is a position gain, β is a velocity gain, γ is an acceleration gain, and T is a sampling period. The y direction is also calculated as shown in Equation 1 in a manner similar to the x direction.

The target tracking unit 32 calculates the next predicted position x _pk+1 of the radar target T based on the current smoothed position x _sk , smoothed velocity v _sk and smoothed acceleration a _sk of the radar target T. Then, the next predicted velocity v pk+1 of the radar target T is calculated based on the current smoothed velocity v _sk and smoothed acceleration a _sk of the radar target T. Furthermore, the next predicted acceleration a _{pk+1 of} the radar target T is calculated based on the current smoothed acceleration a _sk of the radar target T. In the αβγ filter, calculation is performed as shown in Equation 2, where α is a position gain, β is a velocity gain, γ is an acceleration gain, and T is a sampling period. The y direction is also calculated as shown in Equation 2 in a manner similar to the x direction.

Therefore, when tracking each radar target T, the radar target trajectory can be smoothed and radar observation noise can be suppressed. However, when tracking multiple radar targets T, it is necessary to prevent jumping between targets when the targets approach each other, as described below.

The upper part of Fig. 4 will explain the current time _tk . The target tracking unit 32 calculates the predicted positions _x1,pk , x2 _,pk at the time _tk for the first and second radar targets T. The representative point extraction unit 24 calculates the observed positions _x1,ok , x2 _,ok at the time tk for the first and second radar targets T. The gate processing unit 31 links the predicted position x1, _pk and the observed position _{x1, ok} at the time _tk for the first radar target T, and links the predicted position x2 _,pk and the observed position x2 _,ok at the time _tk for the second radar target T, based on a method described later. The target tracking unit 32 calculates the smoothed positions _x1,sk , x2 _,sk at the time _tk for the first and second radar targets T.

The lower part of Fig. 4 will explain the next time _tk+1 . The target tracking unit 32 calculates predicted positions _{x1, pk+1} , x2 _{, pk+1} at time _tk+1 for the first and second radar targets T. The representative point extraction unit 24 calculates observed positions _{x1, ok+1} , _{x2, ok+1} at time tk _{+1 for the first and second radar targets T. The gate processing unit 31 links the predicted positions x1, pk+1} and observed positions x1 _, ok+1 at time tk+ ₁ for the first radar target T, and links the predicted positions x2 _{, pk+1} and observed positions x2, _{ok+1 at} time _tk+1 for the second radar target T, based on a method described later. The target tracking unit 32 calculates smoothed positions _x1,sk+1 and _x2,sk+1 at time _tk+1 for the first and second radar targets T. The subsequent processing is substantially the same as the processing described above.

(Details of the first gate process of the present disclosure)
The first gate processing of the present disclosure will be described in detail. The procedure of the first gate processing of the present disclosure is shown in Fig. 5. The gate processing unit 31 sets a position gate around the current predicted position of one radar target T (step S1). Then, it is confirmed whether or not the current observed positions of multiple radar targets T exist within the position gate (step S2).

When the current observation positions of multiple radar targets T exist within the position gate (step S2, YES), the gate processing unit 31 selects the radar target T having the current observation Doppler speed closest to the Doppler component of the current predicted speed of the one radar target T (step S3). Then, the current predicted position of the one radar target T and the current observation position of the selected radar target T are linked and output to the target tracking unit 32 (step S4).

When there are no current observation positions of multiple radar targets T within the position gate, and only the current observation position of the one radar target T exists (step S2, NO), the gate processing unit 31 links the current predicted position of the one radar target T with the current observation position of the one radar target T and outputs them to the target tracking unit 32 (step S5).

As a specific example of the first gate processing of the present disclosure, the case of passing each other is shown in FIG. 6. In the XY plane in the left column of FIG. 6, radar target T9 is a person moving away from radar system R, and radar target T10 is a person approaching radar system R. When radar target T9 and radar target T10 approach each other and pass each other, this prevents the radar target T9 and radar target T10 from being mistakenly recognized as a change of direction.

In the XY plane in the center of FIG. 6, the predicted position of radar target T9 is indicated by a black circle, and the observed position of radar target T9 is indicated by a black square. Position gate PG9 is set around the predicted position of radar target T9. The predicted position of radar target T10 is indicated by a white circle, and the observed position of radar target T10 is indicated by a white square. Position gate PG10 is set around the predicted position of radar target T10. The predicted positions of radar targets T9 and T10 are quite close to each other, and position gates PG9 and PG10 overlap each other, the observed position of radar target T9 is inside position gates PG9 and PG10, and the observed position of radar target T10 is inside position gates PG9 and PG10.

In the XYV space (V is Doppler velocity) in the right column of FIG. 6, the Doppler component (>0) of the predicted velocity of radar target T9 is shown by a black circle, and the observed Doppler velocity (>0) of radar target T9 is shown by a black square. The Doppler component (<0) of the predicted velocity of radar target T10 is shown by a white circle, and the observed Doppler velocity (<0) of radar target T10 is shown by a white square. Here, the degree of agreement between the Doppler components of the predicted velocities of radar targets T9 and T10 and the observed Doppler velocities of radar targets T9 and T10 is confirmed. Therefore, the predicted position of radar target T9 can be correctly linked to the observed position of radar target T9. And the predicted position of radar target T10 can be correctly linked to the observed position of radar target T10.

As a specific example of the first gate processing of the present disclosure, the case of overtaking is shown in FIG. 7. In the XY plane in the left column of FIG. 7, radar target T11 is a person moving away from the radar system R, and radar target T12 is also a person moving away from the radar system R. As radar target T11 approaches and overtakes radar target T12, this is prevented from being erroneously recognized as a speed switch.

In the XY plane in the center of FIG. 7, the predicted position of radar target T11 is indicated by a black circle, and the observed position of radar target T11 is indicated by a black square. Position gate PG11 is set around the predicted position of radar target T11. The predicted position of radar target T12 is indicated by a white circle, and the observed position of radar target T12 is indicated by a white square. Position gate PG12 is set around the predicted position of radar target T12. The predicted positions of radar targets T11 and T12 are quite close to each other, and position gates PG11 and PG12 overlap each other, with the observed position of radar target T11 existing inside position gates PG11 and PG12, and the observed position of radar target T12 existing inside position gates PG11 and PG12.

In the XYV space (V is Doppler velocity) in the right column of FIG. 7, the Doppler component (high speed) of the predicted speed of the radar target T11 is shown by a black circle, and the observed Doppler velocity (high speed) of the radar target T11 is shown by a black square. The Doppler component (low speed) of the predicted speed of the radar target T12 is shown by a white circle, and the observed Doppler velocity (low speed) of the radar target T12 is shown by a white square. Here, the degree of agreement between the Doppler components of the predicted speeds of the radar targets T11 and T12 and the observed Doppler velocities of the radar targets T11 and T12 is confirmed. Thus, the predicted position of the radar target T11 can be correctly linked to the observed position of the radar target T11. And the predicted position of the radar target T12 can be correctly linked to the observed position of the radar target T12.

As a specific example of the first gate processing of the present disclosure, the case of walking close to a wall is shown in Figure 8. In the XY plane in the left column of Figure 8, radar target T13 is a wall that should be recognized as stationary clutter, and radar target T14 is a person moving away from the radar system R. As radar target T14 walks along radar target T13, it prevents it from being erroneously recognized as being stationary.

In the XY plane in the center of FIG. 8, the predicted position of radar target T13 is indicated by a black circle, and the observed position of radar target T13 is indicated by a black square. Position gate PG13 is set around the predicted position of radar target T13. The predicted position of radar target T14 is indicated by a white circle, and the observed position of radar target T14 is indicated by a white square. Position gate PG14 is set around the predicted position of radar target T14. The predicted positions of radar targets T13 and T14 are quite close to each other, and position gates PG13 and PG14 overlap each other, with the observed position of radar target T13 existing inside position gates PG13 and PG14, and the observed position of radar target T14 existing inside position gates PG13 and PG14.

In the XYV space (V is Doppler velocity) in the right column of FIG. 8, the Doppler component of the predicted velocity of the radar target T13 (=0) is shown by a black circle, and the observed Doppler velocity of the radar target T13 (=0) is shown by a black square. The Doppler component of the predicted velocity of the radar target T14 (>0) is shown by a white circle, and the observed Doppler velocity of the radar target T14 (>0) is shown by a white square. Here, the degree of agreement between the Doppler components of the predicted velocities of the radar targets T13 and T14 and the observed Doppler velocities of the radar targets T13 and T14 is confirmed. Thus, the predicted position of the radar target T13 can be correctly linked to the observed position of the radar target T13. And the predicted position of the radar target T14 can be correctly linked to the observed position of the radar target T14.

In this way, even when multiple radar targets T are close to each other, the multiple radar targets T can be tracked with high accuracy by using the Doppler velocity information of each radar target T and correctly linking the predicted position and observed position of each radar target T. Note that when multiple radar targets T are in parallel, it is sufficient to track the multiple radar targets T together without correctly linking the predicted position and observed position of each radar target T.

A specific example of the setting of a position gate according to the present disclosure is shown in FIG. 9. In the left column of FIG. 9, the position gate PG is a circle set around the predicted position of the radar target T. In other words, the gate width of the position gate PG is set similarly for both the same direction and the opposite direction relative to the predicted speed of the radar target T. Here, the gate width of the position gate PG may be set wider the greater the variance value of the observed positions of the cluster of the radar target T.

In the middle column of Figure 9, the position gate PG is a circle that is set around the predicted position of the radar target T, but not at its center. In other words, the gate width of the position gate PG is set wider in the same direction as the predicted speed of the radar target T than in the opposite direction. Here, the position gate PG in the left column of Figure 9 can be moved parallel to the same direction as the predicted speed of the radar target T.

In the right column of FIG. 9, the position gate PG is an ellipse that is set around the predicted position of the radar target T, rather than centered on it. In other words, the gate width of the position gate PG is set wider in the same direction as the predicted speed of the radar target T than in the opposite direction. Here, the position gate PG in the middle column of FIG. 9 can be compressed in the direction perpendicular to the predicted speed of the radar target T.

In this way, the observation position of each radar target T can be reliably linked in the same direction as the predicted speed of each radar target T, and the probability of picking up noise in the opposite direction to the predicted speed of each radar target T can be reliably reduced, and the area of the position gate PG can be suppressed.

The predicted speed of each radar target T is in any direction over 360° as seen from the radar system R, and the direction in which the position gate PG is narrowed is not limited to two directions.

(Details of the second gate process of the present disclosure)
The second gate processing of the present disclosure will be described in detail. The procedure of the second gate processing of the present disclosure is shown in Fig. 10. The gate processing unit 31 sets a position gate around the current predicted position of one radar target T (step S11). Then, it is confirmed whether or not the current observed positions of multiple radar targets T exist within the position gate (step S12).

When the current observation positions of multiple radar targets T exist within the position gate (step S12, YES), the gate processing unit 31 sets a speed gate around the Doppler component of the current predicted speed of one radar target T (step S13). Then, within the speed gate, the radar target T with the current observed Doppler speed is selected (step S14). Furthermore, the current predicted position of the one radar target T and the current observed position of the selected radar target T are linked and output to the target tracking unit 32 (step S15).

When there are no current observation positions of multiple radar targets T within the position gate, and only the current observation position of the one radar target T exists (step S12, NO), the gate processing unit 31 links the current predicted position of the one radar target T with the current observation position of the one radar target T and outputs them to the target tracking unit 32 (step S16).

As a specific example of the second gate processing of the present disclosure, the case of passing each other is shown in the left column of FIG. 11. The passing shown in the left column of FIG. 11 is similar to the passing shown in FIG. 6.

The predicted position and Doppler components of the predicted speed of radar target T9 are shown with black circles, and the observed position and observed Doppler speed of radar target T9 are shown with black squares. The cross section of the speed gate VG9 including the XY plane is set around the predicted position of radar target T9. The cross section of the speed gate VG9 including the V axis (V is Doppler speed) is set around the Doppler components of the predicted speed of radar target T9. The observed position and observed Doppler speed of radar target T10 are shown with white squares. The predicted position, Doppler components of the predicted speed, and speed gate of radar target T10 are not shown to simplify the left column of FIG. 11.

The observed position and observed Doppler velocity of radar target T9 are inside speed gate VG9, but the observed position and observed Doppler velocity of radar target T10 are not inside speed gate VG9. Therefore, the predicted position of radar target T9 can be correctly linked to the observed position of radar target T9. And, the predicted position of radar target T10 can be correctly linked to the observed position of radar target T10 (not shown in the left column of FIG. 11).

As a specific example of the second gate processing of the present disclosure, the case of overtaking is shown in the middle column of FIG. 11. The overtaking shown in the middle column of FIG. 11 is similar to the overtaking shown in FIG. 7.

The predicted position and Doppler components of the predicted speed of the radar target T12 are shown with white circles, and the observed position and observed Doppler speed of the radar target T12 are shown with white squares. The cross section of the speed gate VG12 including the XY plane is set around the predicted position of the radar target T12. The cross section of the speed gate VG12 including the V axis (V is Doppler speed) is set around the Doppler components of the predicted speed of the radar target T12. The observed position and observed Doppler speed of the radar target T11 are shown with black squares. The predicted position, Doppler components of the predicted speed, and speed gate of the radar target T11 are not shown to simplify the middle column of Figure 11.

The observed position and observed Doppler velocity of radar target T12 are inside the speed gate VG12, but the observed position and observed Doppler velocity of radar target T11 are not inside the speed gate VG12. Therefore, the predicted position of radar target T12 and the observed position of radar target T12 can be correctly linked. And, the predicted position of radar target T11 and the observed position of radar target T11 can be correctly linked (not shown in the middle column of Figure 11).

As a specific example of the second gate processing of the present disclosure, the case of wall walking is shown in the right column of FIG. 11. The wall walking shown in the right column of FIG. 11 is similar to the wall walking shown in FIG. 8.

The predicted position and Doppler components of the predicted speed of the radar target T14 are shown with white circles, and the observed position and observed Doppler speed of the radar target T14 are shown with white squares. The cross section of the speed gate VG14 including the XY plane is set around the predicted position of the radar target T14. The cross section of the speed gate VG14 including the V axis (V is Doppler speed) is set around the Doppler components of the predicted speed of the radar target T14. The observed position and observed Doppler speed of the radar target T13 are shown with black squares. The predicted position, Doppler components of the predicted speed, and speed gate of the radar target T13 are not shown to simplify the right column of Figure 11.

The observed position and observed Doppler velocity of radar target T14 are inside the speed gate VG14, but the observed position and observed Doppler velocity of radar target T13 are not inside the speed gate VG14. Therefore, the predicted position of radar target T14 can be correctly linked to the observed position of radar target T14. And, the predicted position of radar target T13 can be correctly linked to the observed position of radar target T13 (not shown in the right column of Figure 11).

In this way, even when multiple radar targets T are close to each other, multiple radar targets T can be tracked with high accuracy by setting not only the position gates but also the speed gates for each radar target T and then correctly linking the predicted position and observed position of each radar target T. Note that when multiple radar targets T are in parallel, it is sufficient to track multiple radar targets T together without correctly linking the predicted position and observed position of each radar target T.

Specific examples of speed gate settings according to the present disclosure are shown in Figures 12 and 13. Figure 12 deals with sudden speed changes. Figure 13 reduces the probability of picking up noise.

In the left column of FIG. 12, the variance value of the observed Doppler velocity is small for the observation signal point cluster of radar target T15. Therefore, the gate width of the velocity gate VG15 in the V-axis direction (V is Doppler velocity) is set narrower. Specifically, the velocity gate width is set as the sum of the Doppler component of the predicted velocity of radar target T15 and a variable that changes based on the variance value of the observed Doppler velocity of radar target T15 (a small variable corresponding to a small variance value). Furthermore, a constant may be added to this sum to set the velocity gate width. In other words, since the velocity gate width mainly includes the Doppler component of the predicted velocity of radar target T15, it becomes a stable gate width that reflects the actual almost constant velocity.

In the right column of FIG. 12, the variance value of the observed Doppler velocity is large for the observation signal point cluster of radar target T16. Therefore, the gate width of the velocity gate VG16 in the V-axis direction (V is Doppler velocity) is set to be wide. Specifically, the velocity gate width is set as the sum of the Doppler component of the predicted velocity of radar target T16 and a variable that changes based on the variance value of the observed Doppler velocity of radar target T15 (a large variable corresponding to a large variance value). Furthermore, a constant may be added to this sum to set the velocity gate width. In other words, since the velocity gate width includes a large amount of the variance value of the observed Doppler velocity of radar target T16, it becomes a flexible gate width that is not influenced by the almost constant velocity in the past.

In this way, even when each radar target T changes speed suddenly, the observed Doppler velocity of each radar target T can be prevented from departing from the inside of each speed gate, and each radar target T can be prevented from being determined to be a new target that has suddenly appeared. Examples of such radar targets T include pedestrians and animals (birds, bears, etc.).

In each column of FIG. 12, the speed gates VG15 and VG16 are ellipsoids in the XYV space (V is the Doppler velocity). The cross sections of the speed gates VG15 and VG16 including the XY plane are circles set around the predicted positions of the radar targets T15 and T16. The cross sections of the speed gates VG15 and VG16 including the V axis are ellipses set around the Doppler components of the predicted speeds of the radar targets T15 and T16. In other words, the gate widths of the speed gates VG15 and VG16 in the XYV directions are set in the same way for the predicted speeds of the radar targets T15 and T16 in both the same and opposite directions. Here, the gate widths of the speed gates VG15 and VG16 in the XY directions may be set wider as the variance of the observation positions of the clusters of the radar targets T15 and T16 increases, as in the case of the columns of FIG. 9.

In each column of FIG. 13, the speed gate VG is also a spheroid in XYV space (V is Doppler velocity). The cross section of the speed gate VG that includes the XY plane is a circle that is set around the predicted position of the radar target T, not at its center. The cross section of the speed gate VG that includes the V axis is an ellipse that is set around the Doppler component of the predicted velocity of the radar target T. In other words, the gate width of the speed gate VG in each of the XYV directions is set wider in the same direction than in the opposite direction with respect to the predicted velocity of the radar target T. Here, the speed gates VG15 and VG16 in each column of FIG. 12 can be translated in the same direction as the predicted velocity of the radar targets T15 and T16.

In this way, the observed Doppler velocity of each radar target T can be reliably linked in the same direction as the predicted velocity of each radar target T, and the probability of picking up noise in the opposite direction to the predicted velocity of each radar target T can be reliably reduced, and the volume of the velocity gate VG can be suppressed.

The predicted speed of each radar target T is in any direction over 360° as seen from the radar system R, and the direction in which the speed gate VG is narrowed is not limited to two directions.

The radar target tracking device and radar target tracking program disclosed herein can be applied to in-vehicle wideband MIMO radar, advanced driver assistance systems (ADAS), etc.

R: radar system T1, T3, T, T9, T10, T11, T12, T13, T14, T15, T16: radar target T2, T4, T5, T6, T7, T8: tracked target G1, G3, G5, G6, G7, G8: gates PG9, PG10, PG11, PG12, PG13, PG14, PG: position gates VG9, VG12, VG14, VG15, VG16, VG: speed gates 1: radar transceiver 2: radar target observation device 3: radar target tracking device 21: signal processing unit 22: signal point extraction unit 23: clustering unit 24: representative point extraction unit 31: gate processing unit 32: target tracking unit

Claims (6)

a target tracking unit that calculates a current smoothed position of the radar target based on a current predicted position and observed position of the radar target, calculates a current smoothed velocity of the radar target based on a current predicted position, observed position and predicted velocity of the radar target, calculates a next predicted position of the radar target based on the current smoothed position and smoothed velocity of the radar target, and calculates a next predicted velocity of the radar target based on the current smoothed velocity of the radar target;
a gate processing unit that, when current observation positions of a plurality of radar targets exist within a position gate set around a current predicted position of one of the radar targets, selects the radar target having a current observed Doppler velocity closest to a Doppler component of a current predicted velocity of the one of the radar targets, and links the current predicted position of the one of the radar targets with the current observed position of the selected radar target, and outputs the linked current predicted position of the one of the radar targets to the target tracking unit ;
The gate processing unit sets a width of the position gate wider in the same direction for the current predicted speed of the one radar target than in the opposite direction.
A radar target tracking device comprising: a target tracking unit that calculates a current smoothed position of the radar target based on a current predicted position and observed position of the radar target, calculates a current smoothed velocity of the radar target based on a current predicted position, observed position and predicted velocity of the radar target, calculates a next predicted position of the radar target based on the current smoothed position and smoothed velocity of the radar target, and calculates a next predicted velocity of the radar target based on the current smoothed velocity of the radar target;
a gate processing unit that, when current observation positions of a plurality of radar targets exist within a position gate set around a current predicted position of one of the radar targets, selects the radar target having a current observed Doppler velocity closest to a Doppler component of a current predicted velocity of the one of the radar targets, and links the current predicted position of the one of the radar targets with the current observed position of the selected radar target, and outputs the linked current predicted position of the one of the radar targets to the target tracking unit ;
the gate processing unit selects the radar target having a current observed Doppler velocity within a velocity gate set around a Doppler component of a current predicted velocity of the one radar target as the one radar target among the plurality of radar targets;
The gate processing unit further sets a width of the speed gate wider for the same direction for the current predicted speed of the one radar target than for the opposite direction.
A radar target tracking device comprising: 3. The radar target tracking device according to claim 2 , wherein the gate processing unit sets a width of the velocity gate wider as a variance value of the currently observed Doppler velocity for the observation signal point cluster of the radar target increases. a target tracking step of calculating a current smoothed position of the radar object based on a current predicted position and observed position of the radar object, calculating a current smoothed velocity of the radar object based on a current predicted position, observed position and predicted velocity of the radar object, calculating a next predicted position of the radar object based on the current smoothed position and smoothed velocity of the radar object, and calculating a next predicted velocity of the radar object based on the current smoothed velocity of the radar object;
a gate processing step of selecting, when current observation positions of a plurality of radar targets exist within a position gate set around a current predicted position of one of the radar targets, the radar target having a current observed Doppler velocity closest to a Doppler component of a current predicted velocity of the one of the radar targets, and linking the current predicted position of the one of the radar targets with the current observed position of the selected radar target, and outputting the linked current predicted position of the one of the radar targets to the target tracking step;
Run the following on your computer :
The gate processing step sets the width of the position gate wider in the same direction for the current predicted speed of the one radar target than in the opposite direction.
A radar target tracking program comprising : a target tracking step of calculating a current smoothed position of the radar object based on a current predicted position and observed position of the radar object, calculating a current smoothed velocity of the radar object based on a current predicted position, observed position and predicted velocity of the radar object, calculating a next predicted position of the radar object based on the current smoothed position and smoothed velocity of the radar object, and calculating a next predicted velocity of the radar object based on the current smoothed velocity of the radar object;
a gate processing step of selecting, when current observation positions of a plurality of radar targets exist within a position gate set around a current predicted position of one of the radar targets, the radar target having a current observed Doppler velocity closest to a Doppler component of a current predicted velocity of the one of the radar targets, and linking the current predicted position of the one of the radar targets with the current observed position of the selected radar target, and outputting the linked current predicted position of the one of the radar targets to the target tracking step;
Run the following on your computer :
The gate processing step includes selecting, as the one of the plurality of radar targets, the radar target having a current observed Doppler velocity within a velocity gate set around a Doppler component of a current predicted velocity of the one of the radar targets;
The gate processing step further includes setting a width of the speed gate wider for the same direction for the current predicted speed of the one radar target than for the opposite direction.
A radar target tracking program comprising : 6. The radar target tracking program according to claim 5 , wherein the gate processing step sets a width of the velocity gate wider as a variance value of the currently observed Doppler velocity for the observation signal point cluster of the radar target increases.

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