Vehicular front monitoring apparatus

• US 6,265,991 B1
• Filed: 05/09/2000
• Issued: 07/24/2001
• Est. Priority Date: 12/10/1999
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Automotive Safety and Anti-Polution Technology Research Alliance, Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Okamura, Shigekazu, Nishida, Minoru, Nishiwaki, Takeshi
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/566,082
• Time in Patent Office: 441 Days
• Field of Search: 340/435, 340/436, 340/901, 340/903, 340/904, 340/905, 342/70, 342/72, 701/42, 701/48, 701/28, 180/167, 382/104, 382/281, 382/291
• US Class Current: 340/903
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2552/30 Road curve radius
• 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 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G08G 1/165 for passive traffic, e.g. including static obstacles, trees
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

A vehicular front monitoring apparatus which can reliably recognize a road configuration ahead of an own-vehicle through simpler computation. The apparatus comprises a distance measuring unit for radiating electromagnetic waves or the likes in plural directions, and detecting distances from an own-vehicle to a plurality of objects around the own-vehicle and lateral positions of the objects relative to a running direction of the own-vehicle, thereby measuring object positional data on coordinates defined by the running direction and a transverse direction of the own-vehicle; a road curvature estimating unit for estimating a curvature of a road ahead of the own-vehicle through Hough transform of the object positional data measured by the distance measuring unit; and a vehicle'"'"'s own lane determining unit for determining whether other vehicles running ahead are in the same lane as the own-vehicle or not based on the curvature of the road estimated by the road curvature estimating unit.

Claims

1. A vehicular front monitoring apparatus, comprising:

a distance measuring unit which radiates electromagnetic waves in plural directions and detects distances from an own-vehicle to a plurality of objects around the own-vehicle and lateral positions of the objects relative to a running direction of the own-vehicle to measure object positional data (xi, yi) on coordinates defined by the running direction (yi) and a lateral direction (xi) to the running direction;

a road curvature estimating unit which estimates the curvature of a road ahead of the own-vehicle by setting a plane defined by a lateral shift from a center line of the own-vehicle and the curvature of the road and performing a Hough transform of the measured object positional data, wherein a memory array is defined by dividing the plane into a plurality of zones of a mesh pattern and the curvature of the road is determined by an array element having a maximum occurrence is sought and an array number corresponding to the array element is selected; and

a lane determining unit which determines whether other vehicles running ahead of said own vehicle are in the same lane as the own-vehicle or not.

2. A vehicular front monitoring apparatus according to claim 1, wherein the lane determining unit determines whether other vehicles running ahead are in the same lane as the own-vehicle or not based on the curvature of the road estimated by said road curvature estimating unit.

3. A vehicular front monitoring apparatus according to claim 2, wherein said road curvature estimating unit performs Hough transform using the following relational formula:

4. A vehicular front monitoring apparatus according to claim 1, further comprising:

a speed measuring unit which measures a speed of the own-vehicle;

a yaw rate measuring unit for measuring a yaw rate of the own-vehicle;

a detected-object information storing unit which stores past object positional data measured by said distance measuring unit after transforming the past object positional data, based on outputs of said speed measuring unit and said yaw rate measuring unit; and

a standstill determining unit which determines whether the detected object is stationary or not based on the past object positional data stored in said detected-object information storing unit and a newest object positional data measured by said distance measuring unit,

wherein the road curvature estimating unit estimates the curvature of a road ahead of the own-vehicle through the Hough transform of the positional data of objects that have been determined to be stationary by said standstill determining unit and wherein the lane determining unit determines whether other vehicles running ahead of the own vehicle are in the same lane as the own-vehicle or not, based on the curvature of the road estimated by said road curvature estimating unit.

5. A vehicular front monitoring apparatus according to claim 4, wherein said road curvature estimating unit performs Hough transform using the following relational formula:

6. A vehicular front monitoring apparatus according to claim 4, wherein the standstill determining unit determines whether the detected object is stationary by comparing the past object positional data stored in said detected-object information storing unit and the newest object positional data.

7. A vehicular front monitoring apparatus according to claim 6, wherein the past object positional data is stored in said detected-object information storing unit after being transformed into positions on coordinates wherein an origin point is defined as a position of the own-vehicle at a current detection time, based on a distance of movement of the own-vehicle obtained by said own-vehicle speed measuring unit and a change in running direction of the own-vehicle obtained by said yaw rate detecting unit.

8. A vehicular front monitoring apparatus according to claim 4, wherein the past object positional data is stored in said detected-object information storing unit after being transformed into positions on coordinates wherein an origin point is defined as a position of the own-vehicle at a current detection time, based on a distance of movement of the own-vehicle obtained by said own-vehicle speed measuring unit and a change in running direction of the own-vehicle obtained by said yaw rate detecting unit.

9. A vehicular front monitoring apparatus according to claim 4, wherein the yaw rate is measured by a yaw rate sensor mounted on a vehicle.

10. A vehicular front monitoring apparatus according to claim 4, wherein the yaw rate is measured based on outputs of a steering wheel sensor and a vehicle speed sensor.

11. A vehicular front monitoring apparatus according to claim 1, further comprising:

a speed measuring unit for measuring a speed of the own-vehicle;

a yaw rate measuring unit for measuring a yaw rate of the own-vehicle;

a detected-object information storing unit which stores past object positional data measured by said distance measuring unit after transforming the past object positional data, based on outputs of said speed measuring unit and said yaw rate measuring unit;

a standstill determining unit which determines whether the detected object is stationary or not based on the past object positional data stored in said detected-object information storing unit and a newest object positional data measured by said distance measuring unit; and

a moving-object information storing unit which stores positional data of objects that have been determined to be not stationary by said standstill determining unit, after the positional data of the objects have been transformed into positions on coordinates wherein an origin point is defined as a position of the own vehicle at a current detection time, based on outputs of said speed measuring unit and said yaw rate measuring unit;

wherein the road curvature estimating unit estimates the curvature of a road ahead of the own-vehicle through the Hough transform of newest positional data of objects that have been determined to be stationary by said standstill determining unit, newest positional data of the objects that have been determined to be not stationary by said standstill determining unit, and the past object positional data stored in said moving-object information storing unit and wherein the vehicle'"'"'s own lane determining unit determines whether other vehicles running ahead of the own-vehicle are in the same lane as the own-vehicle or not, based on the curvature of the road estimated by said road curvature estimating unit.

12. A vehicular front monitoring apparatus according to claim 11, wherein said road curvature estimating unit performs Hough transform using the following relational formula:

13. A vehicular front monitoring apparatus according to claim 11, wherein the standstill determining unit determines whether the detected object is stationary by comparing the past object positional data stored in said detected-object information storing unit and the newest object positional data.

14. A vehicular front monitoring apparatus according to claim 13, wherein the past object positional data is stored in said detected-object information storing unit after being transformed into positions on coordinates wherein an origin point is defined as a position of the own-vehicle at a current detection time, based on a distance of movement of the own-vehicle obtained by said own-vehicle speed measuring unit and a change in running direction of the own-vehicle obtained by said yaw rate detecting unit.

15. A vehicular front monitoring apparatus according to claim 11, wherein the past object positional data is stored in said detected-object information storing unit after being transformed into positions on coordinates wherein an origin point is defined as a position of the own-vehicle at a current detection time, based on a distance of movement of the own-vehicle obtained by said own-vehicle speed measuring unit and a change in running direction of the own-vehicle obtained by said yaw rate detecting unit.

16. A vehicular front monitoring apparatus according to claim 1, further comprising:

a speed measuring unit for measuring a speed of the own-vehicle;

a yaw rate measuring unit for measuring a yaw rate of the own-vehicle;

a first road curvature estimating unit which estimates the curvature of a road ahead of the own-vehicle through Hough transform of the object positional data measured by said distance measuring unit; and

a second road curvature estimating unit which estimates the curvature of a road based on outputs of said speed measuring unit and said yaw rate measuring unit, and changes an estimation range of the curvature of the road of said first road curvature estimating unit,

wherein the lane determining unit determines whether other vehicles running ahead of the own-vehicle are in the same lane as the own-vehicle or not, based on the curvature of the road estimated by said first road curvature estimating unit.

17. A vehicular front monitoring apparatus according to claim 16, wherein said road curvature estimating unit performs Hough transform using the following relational formula:

18. A vehicular front monitoring apparatus according to claim 1, further comprising:

a vehicle speed detecting unit for detecting a speed of an own-vehicle,

wherein the road curvature estimating unit estimates the curvature of a road ahead of the own-vehicle through Hough transform of the object positional data measured by said distance measuring unit and wherein the lane determining unit determines whether other vehicles running ahead of the own-vehicle are in the same lane as the own-vehicle or not, based on the curvature of the road estimated by said road curvature estimating unit, and wherein an estimation range and estimation accuracy of the curvature of the road estimated by said road curvature estimating unit changes depending on the vehicle speed detected by said speed detecting unit.

19. A vehicular front monitoring apparatus according to claim 18, wherein assuming that coordinates of the detected object positional data with an origin point defined as a position of the own-vehicle are (xi, yi), the curvature of the road is ρ

, and a lateral shift amount of the detected object from a center of the own-vehicle is di, said road curvature estimating means performs Hough transform using the following relational formula;

20. A vehicular front monitoring apparatus, comprising:

a distance measuring unit which radiates electromagnetic waves in plural directions and detects distances from an own-vehicle to a plurality of objects around the own-vehicle and lateral positions of the objects relative to a running direction of the own-vehicle to measure object positional data (xi, yi) on coordinates defined by the running direction (yi) and a lateral direction (xi) to the running direction;

a road curvature estimating unit which estimates the curvature of a road ahead of the own-vehicle through a Hough transform of the measured object positional data;

a lane determining unit which determines whether other vehicles running ahead of said own vehicle are in the same lane as the own-vehicle or not;

a speed measuring unit which measures a speed of the own-vehicle;

a yaw rate measuring unit for measuring a yaw rate of the own-vehicle;

a detected-object information storing unit which stores past object positional data measured by said distance measuring unit after transforming the past object positional data, based on outputs of said speed measuring unit and said yaw rate measuring unit; and

a standstill determining unit which determines whether the detected object is stationary or not based on the past object positional data stored in said detected-object information storing unit and a newest object positional data measured by said distance measuring unit,

wherein the road curvature estimating unit estimates the curvature of a road ahead of the own-vehicle through the Hough transform of the positional data of objects that have been determined to be stationary by said standstill determining unit and wherein the lane determining unit determines whether other vehicles running ahead of the own vehicle are in the same lane as the own-vehicle or not, based on the curvature of the road estimated by said road curvature estimating unit.

21. A method of determining configurations of a road and detecting positions of objects in the vicinity of a vehicle, comprising the steps of:

a) radiating electromagnetic waves in plural directions from said vehicle;

b) collecting the radiated electromagnetic waves and detecting distances from said vehicle to a plurality of objects around said vehicle;

c) determining lateral positions of the objects in the vicinity of the vehicle relative to a running direction of said vehicle to measure object positional data (xi, yi) on coordinates defined by the running direction (yi) and a lateral direction (xi) to the running direction;

d) estimating a curvature of the road ahead of the own-vehicle through a Hough transform of the measured object positional data in step (c); and

e) determining whether other vehicles running ahead of said vehicle are in the same lane as the own-vehicle or not based on the road curvature estimation of step (d).

22. The method according to claim 21, wherein the step of estimating the curvature of the road comprises:

d1) setting a plane (d−

ρ

plane) defined by a lateral shift amount d from a center line of said vehicle and the curvature ρ

of the road, for performing Hough transform of object positional data (xi,yi);

d2) dividing the plane into a number Nd of zones in the d-direction and a number Nρ

of zones in the ρ

-direction, thereby defining a mesh pattern;

d3) setting a memory array M_pρ

corresponding to the mesh pattern of step (c2);

d4) determining the curvature of the road ρ

est based on an array element having a maximum value using the following formula;