Obstacle detection system for vehicle

• US 20070285305A1
• Filed: 06/07/2007
• Published: 12/13/2007
• Est. Priority Date: 06/13/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Tanaka, Hideaki
• Granted Patent: US 7,498,972 B2
• Time in Patent Office: Days
• US Class Current: 342/70
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G08G 1/163 involving continuous checking

Abstract

An obstacle detection system determines a probability distribution of existence of an obstacle object corresponding to a distance in an irradiation direction of a transmission wave based on detected strength data per scanning-angle supplied from a radar device. A peak-value of the strength data becomes a maximum probability of existence of the obstacle. The probability distribution has a range gradually decreasing before and after the peak-value. Even if the position indicated by the maximum probability of existence of the obstacle object is different from an actual distance to the obstacle object, it hardly occurs that the probability of existence at an actual position of the obstacle object becomes zero. This eliminates occurrence of separation/association errors. Primary and secondary existence probability relationships made based on the probability distribution are combined. Using the combined one further decreases the error detection.

Claims

1. An obstacle detection system for a vehicle capable of detecting objects as obstacles existing around a vehicle based on a detection signal irradiated toward and reflected from the objects per predetermined detecting period of scanning the detection signal, comprising:

an object sensor configured to detect existence/non-existence and a position of an object within a predetermined detection range outside of the vehicle based on the detection signal received;

probability distribution determining means configured to determine an existence probability distribution of the obstacle in a detecting direction toward the obstacle from the object sensor, and a maximum value in the existence probability distribution being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle in the detecting direction;

primary probability relationship making means configured to make a primary existence probability relationship representing a primary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions throughout the entire of the predetermined detection range;

combining means configured to make a combined existence probability relationship by combining the primary existence probability relationship obtained in a current detecting period and a secondary existence probability relationship estimated based on a previous detection signal in a previous detecting period corresponding to the primary existence probability relationship of the current detecting period;

speed calculating means configured to calculate an estimated moving speed of the obstacle during a period from the detecting period of two times before to the previous detecting period based on the combined existence probability relationship obtained in the previous detecting period and the combined existence probability relationship obtained in the detecting period of two times before; and

secondary probability relationship making means configured to make the secondary existence probability relationship based on the estimated moving speed of the obstacle and the combined existence probability relationship during the previous detecting period.

6. The obstacle detection system for a vehicle according to claim 1, wherein the primary existence probability relationship and the secondary existence probability relationship are expressed in an absolute coordinate system.

11. The obstacle detection system for a vehicle according to claim 1, wherein the range of the existence probability distribution in which the probability of existence is gradually decreased is within two or three times of a standard deviation of the probability of position of the obstacle from the maximum value in the existence probability distribution.

2. An obstacle detection system for a vehicle capable of detecting objects as obstacles existing around a vehicle based on a detection signal irradiated toward the objects and reflected from the objects per predetermined detecting period of scanning the detection signal, comprising:

an object sensor comprising a primary object sensor and a secondary object sensor which are different in detecting manner to each other, and each object sensor configured to detect existence/non-existence and a position of an object within a predetermined detection range outside of the vehicle based on the detection signal received;

primary probability distribution determining means configured to determine an existence probability distribution of the obstacle in a primary detecting direction toward the obstacle from the primary object sensor, and a maximum value in the existence probability distribution being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle in the primary detecting direction;

secondary probability distribution determining means configured to determine an existence probability distribution of the obstacle in a secondary detecting direction toward the obstacle from the secondary object sensor, and a maximum value in the existence probability distribution being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle in the secondary detecting direction;

probability relationship making means configured to make a primary existence probability relationship representing a primary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions obtained by the primary probability distribution determining means throughout the entire of the predetermined detection range, and further to make a secondary existence probability relationship representing a secondary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions obtained by the secondary probability distribution determining means throughout the entire of the predetermined detection range; and

combining means configured to make a combined existence probability relationship by combining the primary existence probability relationship and the secondary existence probability relationship made by the probability relationship making means.

7. The obstacle detection system for a vehicle according to claim 2, wherein the primary existence probability relationship and the secondary existence probability relationship are expressed in an absolute coordinate system.

12. The obstacle detection system for a vehicle according to claim 2, wherein the range of the existence probability distribution in which the probability of existence is gradually decreased is within two or three times of a standard deviation of the probability of position of the obstacle from the maximum value in the existence probability distribution.

3. An obstacle detection system for a vehicle capable of detecting objects as obstacles existing around a vehicle, comprising:

a radar device configured to irradiate a transmission wave to the outside of a vehicle within a predetermined scanning-angle range per predetermined scanning period, and to receive the transmission wave reflected by an object as an obstacle and to detect existence/non-existence and position of the obstacle based on the reflected transmission wave;

probability distribution determining means configured to determine an existence probability distribution of the obstacle to a distance of the transmission wave toward its irradiation direction based on a relationship between an elapsed time counted from the irradiation of the transmission wave and the strength of the reflected transmission wave, and a maximum value in the strength of the reflected transmission wave being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle;

primary probability relationship making means configured to make a primary existence probability relationship representing a primary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions determined by the probability distribution determining means based on the transmission wave irradiated throughout the entire of the scanning-angle range;

combining means configured to make a combined existence probability relationship by combining the primary existence probability relationship obtained in a current scanning period and a secondary existence probability relationship estimated based on a previous detection signal in a previous scanning period corresponding to the primary existence probability relationship of the current scanning period;

speed calculating means configured to calculate an estimated moving speed of the obstacle during a period from the scanning period of two times before to the previous scanning period based on the combined existence probability relationship obtained in the previous scanning period and the combined existence probability relationship obtained in the scanning period of two times before; and

secondary probability relationship making means configured to make the secondary existence probability relationship based on the estimated moving speed of the obstacle and the combined existence probability relationship during the previous scanning period.

5. The obstacle detection system for a vehicle according to claim 3, wherein

the radar device comprises a primary radar device and a secondary radar device which irradiate different types of transmission waves to each other,

the probability distribution determining means comprises:

primary probability distribution determining means and;

secondary primary probability distribution determining means, wherein

the primary probability distribution determining means is configured to determine an existence probability distribution of the obstacle to a distance of the transmission wave toward its irradiation direction based on a relationship between an elapsed time counted from the irradiation of the transmission wave by the primary radar device and the strength of the reflected transmission wave, and a maximum value in the strength of the reflected transmission wave is used as a maximum probability of position of the obstacle, and the existence probability distribution has a range gradually decreased before and after the maximum probability of position of the obstacle, and

the secondary probability distribution determining means is configured to determine an existence probability distribution of the obstacle to a distance of the transmission wave toward its irradiation direction based on a relationship between an elapsed time counted from the irradiation of the transmission wave by the secondary radar device and the strength of the reflected transmission wave, and a maximum value in the strength of the reflected transmission wave being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle,

and wherein

the primary probability relationship making means is configured to make a 1-1 existence probability relationship representing a probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions determined by the primary probability distribution determining means based on the transmission wave irradiated throughout the entire of the scanning-angle range, and is also configured to make a 1-2 existence probability relationship representing a probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions determined by the secondary probability distribution determining means based on the transmission wave irradiated throughout the entire of the scanning-angle range.

8. The obstacle detection system for a vehicle according to claim 3, wherein the primary existence probability relationship and the secondary existence probability relationship are expressed in an absolute coordinate system.

10. The obstacle detection system for a vehicle according to claim 5, wherein the primary existence probability relationship and the secondary existence probability relationship are expressed in an absolute coordinate system.

13. The obstacle detection system for a vehicle according to claim 3, wherein the range of the existence probability distribution in which the probability of existence is gradually decreased is within two or three times of a standard deviation of the probability of position of the obstacle from the maximum value in the existence probability distribution.

4. An obstacle detection system for a vehicle capable of detecting objects as obstacles existing around a vehicle, comprising:

a radar device comprising a primary radar device and a secondary radar device which irradiate different types of transmission waves to each other, and each radar device configured to irradiate a transmission wave to the outside of a vehicle within a predetermined scanning-angle range per predetermined scanning period, and to receive the transmission wave reflected by an object as an obstacle and to detect existence/non-existence and position of the obstacle based on the reflected transmission wave;

primary probability distribution determining means configured to determine an existence probability distribution of the obstacle to a distance of the transmission wave toward its irradiation direction based on a relationship between an elapsed time counted from the irradiation of the transmission wave by the primary radar device and the strength of the reflected transmission wave, and a maximum value in the strength of the reflected transmission wave being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle;

secondary probability distribution determining means configured to determine an existence probability distribution of the obstacle to a distance of the transmission wave toward its irradiation direction based on a relationship between an elapsed time counted from the irradiation of the transmission wave by the secondary radar device and the strength of the reflected transmission wave, and a maximum value in the strength of the reflected transmission wave being used as a maximum probability of position of the obstacle, and the existence probability distribution having a range gradually decreased before and after the maximum probability of position of the obstacle;

probability relationship making means configured to make a primary existence probability relationship representing a primary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions determined by the primary probability distribution determining means based on each transmission wave irradiated throughout the entire of the scanning-angle range, and configured to make a secondary existence probability relationship representing a primary probability of existence of the obstacle in a horizontal plane coordinate using a plurality of the existence probability distributions determined by the secondary probability distribution determining means based on each transmission wave irradiated throughout the entire of the scanning-angle range; and

combining means configured to make a combined existence probability relationship by combining the primary existence probability relationship and the secondary existence probability relationship made by the probability relationship making means.

9. The obstacle detection system for a vehicle according to claim 4, wherein the primary existence probability relationship and the secondary existence probability relationship are expressed in an absolute coordinate system.

14. The obstacle detection system for a vehicle according to claim 4, wherein the range of the existence probability distribution in which the probability of existence is gradually decreased is within two or three times of a standard deviation of the probability of position of the obstacle from the maximum value in the existence probability distribution.