RADAR SYSTEM

• US 20110285574A1
• Filed: 12/18/2008
• Published: 11/24/2011
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tsunekawa, Jun
• Granted Patent: US 8,581,776 B2
• Time in Patent Office: Days
• US Class Current: 342/70
• CPC Class Codes: G01S 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 2013/93274 on the side of the vehicles
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

Provided is a radar system which calculates a track of a detected object and can determine whether or not the track is accurate. The radar system includes: a radar section for emitting an electromagnetic wave to an object and receiving a reflected wave reflected from the object to detect position information of the object; a track calculation section for calculating, periodically at a first cycle, a track along which the object moves, on the basis of the position information obtained from the radar section; a first speed calculation section for calculating a first speed at which the object moves, on the basis of pieces of the position information at two different time points having a time interval which is longer than the first cycle; and a track determination section for determining whether or not the track is accurate, on the basis of at least the first speed.

Claims

1. A radar system comprising:

a radar section for emitting an electromagnetic wave to an object and receiving a reflected wave reflected from the object to detect position information of the object;

a track calculation section for calculating, periodically at a first cycle, a track along which the object moves, on the basis of the position information obtained from the radar section;

a first speed calculation section for calculating a first speed at which the object moves, on the basis of pieces of the position information at two different time points having a time interval which is longer than the first cycle; and

a track determination section for determining whether or not the track is accurate, on the basis of at least the first speed.

2. The radar system according to claim 1, wherein the track determination section determines that the track is not accurately calculated, when the first speed is lower than a predetermined threshold.

3. The radar system according to claim 1, further comprising a second speed calculation section for calculating a second speed at which the object moves, on the basis of two adjacent pieces of the position information which are obtained at the first cycle, wherein

the track determination section determines whether or not the track is accurately calculated, on the basis of the first speed and the second speed.

4. The radar system according to claim 3, wherein the track determination section:

calculates a difference value between the first speed and the second speed;

determines that the track is accurately calculated, when the difference value is lower than a predetermined threshold; and

determines that the track is not accurately calculated, when the difference value is equal to or higher than the predetermined threshold.

5. The radar system according to claim 3, wherein the track determination section:

calculates a division value by dividing the second speed by the first speed;

determines that the track is accurately calculated, when the division value is lower than a predetermined threshold; and

determines that the track is not accurately calculated, when the division value is equal to or higher than the predetermined threshold.

6. The radar system according to claim 1, wherein

the radar system is mounted in a vehicle,

the radar system further comprises a predicted collision time calculation section for calculating a predicted collision time to collision of the object with the vehicle, and

only when the predicted collision time satisfies a predetermined condition, the track determination section performs the determination concerning the track.

7. The radar system according to claim 6, wherein the track determination section performs the determination concerning the track when the predicted collision time is longer than a predetermined lower limit time, and does not perform the determination concerning the track when the predicted collision time is equal to or shorter than the lower limit time.

8. The radar system according to claim 6, wherein the track determination section performs the determination concerning the track when the predicted collision time is shorter than a predetermined upper limit time, and does not perform the determination concerning the track when the predicted collision time is equal to or longer than the upper limit time.

9. The radar system according to claim 8, wherein the track determination section performs the determination concerning the track when the predicted collision time is shorter than the upper limit time and longer than a lower limit time which is previously set so as to be shorter than the upper limit time, and does not perform the determination concerning the track when the predicted collision time is equal to or shorter than the lower limit time or when the predicted collision time is equal to or longer than the upper limit time.

10. The radar system according to claim 8, wherein the first speed calculation section calculates the first speed on the basis of:

a piece of the position information of the object at a current time; and

a piece of the position information of the object at a time point when the predicted collision time becomes shorter than the upper limit time.

11. The radar system according to claim 1, wherein

the radar system is mounted in a vehicle,

the radar section further detects a distance from the vehicle to the object, as the position information, and

only when the distance satisfies a predetermined condition, the track determination section performs the determination concerning the track.

12. The radar system according to claim 11, wherein the track determination section performs the determination concerning the track when the distance is longer than a predetermined lower limit distance, and does not perform the determination concerning the track when the distance is equal to or shorter than the lower limit distance.

13. The radar system according to claim 11, wherein the track determination section performs the determination concerning the track when the distance is shorter than a predetermined upper limit distance, and does not perform the determination concerning the track when the distance is equal to or longer than the upper limit distance.

14. The radar system according to claim 13, wherein the track determination section performs the determination concerning the track when the distance is shorter than the upper limit distance and longer than a lower limit distance which is previously set so as to be shorter than the upper limit distance, and does not perform the determination concerning the track when the distance is equal to or shorter than the lower limit distance or when the distance is equal to or longer than the upper limit distance.

15. The radar system according to claim 13, wherein the first speed calculation section calculates the first speed on the basis of:

a piece of the position information of the object at a current time; and

a piece of the position information of the object at a time point when the distance becomes the upper limit distance.

16. The radar system according to claim 1, wherein the first speed calculation section calculates the first speed on the basis of:

a piece of the position information of the object at a current time; and

a piece of the position information of the object at a time point when the object becomes detectable by the radar section.

17. The radar system according to claim 1, wherein the first speed calculation section calculates the first speed on the basis of:

a piece of the position information of the object at a current time; and

a piece of the position information of the object which is obtained at a time point which is a predetermined time before the current time.

18. The radar system according to claim 1, further comprising a meandering determination section for determining whether or not the track calculated by the track calculation section is meandering, wherein

only when the track is meandering, the track determination section determines whether or not the track is accurately calculated.

19. The radar system according to claim 1, wherein

the radar system is mounted in a vehicle, and

the radar system further comprises a collision determination section for determining whether or not a risk of collision of the vehicle with the object is high, by using at least a determination result of the track determination section.

20. The radar system according to claim 19, further comprising a predicted collision time calculation section for calculating a predicted collision time to collision of the object with the vehicle, wherein

the collision determination section includes:

a time determination section for determining whether or not the predicted collision time is shorter than a collision determination value; and

a count section for cumulatively adding an added value each time it is determined that the predicted collision time is shorter than the collision determination value,

the count section;

adds a first value as the added value each time the track determination section determines that the track is accurate; and

adds, as the added value, a second value lower than the first value, each time the track determination section determines that the track is not accurate, and

when a cumulative value of the added value in the count section is equal to or higher than a predetermined threshold, the collision determination section determines that the risk of collision of the vehicle with the object is high.

21. The radar system according to claim 19, wherein the collision determination section determines whether or not the risk of collision of the vehicle with the object is high, on the basis of:

the determination result of the track determination section; and

the track calculated by the track calculation section.

22. The radar system according to claim 21, wherein

the collision determination section includes:

a detected object traveling direction calculation section for calculating a traveling direction of the object on the basis of the track;

an own vehicle traveling direction calculation section for calculating a traveling direction of the vehicle; and

an intersection determination section for determining whether or not the traveling direction of the object intersects the traveling direction of the vehicle, and

when the traveling direction of the object intersects the traveling direction of the vehicle and the track is accurate, the collision determination section makes it easy to determine that the risk of collision of the vehicle with the object is high.