Autonomous vehicle and planar obstacle recognition method

• US 7,742,841 B2
• Filed: 02/23/2006
• Issued: 06/22/2010
• Est. Priority Date: 02/23/2005
• Status: Expired due to Fees

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Inventors: Nishimura, Daisuke, Sakai, Tatsu
• Primary Examiner(s): Tran; Khoi
• Assistant Examiner(s): KING, RODNEY P
• Application Number:
  US11/813,964
• Publication Number:
  US 20090069938A1
• Time in Patent Office: 1,580 Days
• Field of Search: 700/245, 700/255, 700/258, 701/1, 701/23, 701/26, 701/301, 180/9.32
• US Class Current: 700/255
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0257 using a radar radar systems designed for anti-collision purposes between land vehicles or between land vehicle and fixed obstacles G01S13/931
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

In an autonomous vehicle, position of a planar obstacle such as a wall or a fence having apertures is determined. A horizontal plane is scanned with a laser range tinder so as to acquire positional coordinates of a plurality of scanning points. An element vector is formed with each two scanning points so that one acquired former is used as a start point and the other acquired later as an end point of the vector. A plurality of continuous element vectors which satisfy predetermined conditions is selected among the element vectors, and a scanning segment vector is formed by composition of the selected element vectors. When a length of the scanning segment vector is equal to or longer than a predetermined length, it is possible to recognize that a planar obstacle exists along the scanning segment vector.

Claims

1. An autonomous vehicle comprising:

a scanning point acquisition unit scanning a predetermined space at a constant angle or a constant interval with using an electromagnetic wave or an acoustic wave, receiving reflected waves from objects existed in the horizontal plane, and acquiring coordinates of a plurality of scanning points from which the electromagnetic wave or the acoustic wave is reflected;

an element vector forming unit forming an element vector with respect to two scanning points selected among the plurality of scanning points so that one scanning point acquired earlier in time series by the scanning point acquisition unit is used as a start point of the element vector and another scanning point acquired later is used as an end point of the element vector;

an element vector selecting unit selecting a plurality of element vectors which are continued in time series of order of formation by the element vector forming unit, length of each element vector being equal to or shorter than a first predetermined length, a deflection angle of an element vector with respect to another continuing element vector being equal to or smaller than a first predetermined angle, and an integrated value of the deflection angles being equal to or smaller than a second predetermined angle;

a scanning segment vector forming unit forming one scanning segment vector by composing the selected continuing element vectors; and

an obstacle recognizing unit comparing a segment defined by a start point and an end point of the scanning segment vector with a second predetermined length, and recognizing that a planar obstacle exists along the scanning segment vector when the segment is equal to or longer than the second predetermined length.

2. The autonomous vehicle in accordance with claim 1, wherein

the element vector formation unit forms an element vector using only scanning points within a predetermined distance from an arbitrary origin.

3. The autonomous vehicle in accordance with claim 1, wherein

the element vector formation unit sets an arbitrary scanning segment as a first scanning point and a scanning point which is continuous to the first scanning point in time series as a second scanning point so as to form an element vector;

and

when a length of the element vector formed with the first scanning point and the second scanning point is longer than the first predetermined length, the element vector formation unit forms another element vector with the first scanning point and another scanning point which is not continuous to the first scanning point in time series as a new second scanning point.

4. The autonomous vehicle in accordance with claim 3, wherein

when no element vector having a length equal to or shorter than the first predetermined length can be formed with respect to the arbitrary scanning point although attempt to form the element vectors predetermined times, the element vector formation unit sets another scanning point continuous to the arbitrary scanning point in time series as a new first scanning point and attempts to form an element vector with respect to the new first scanning point.

5. The autonomous vehicle in accordance with claim 1, wherein

the element vector formation unit sets an arbitrary scanning segment as a first scanning point, a scanning point which is continuous to the first scanning point in time series as a second scanning point, and a scanning point which is continuous to the second scanning point in time series as a third scanning point so as to form element vectors;

and

when a deflection of a second element vector which is formed by the second scanning point as a start point and the third scanning point as an end point with respect to a first element vector which is formed by the first scanning point as a start point and the second scanning point as an end point is larger than the first predetermined angle, the element vector formation unit excludes the third scanning point and forms an element vector with the second scanning vector and another scanning point which is not continuous to the second scanning point in time series as a new third scanning point.

6. The autonomous vehicle in accordance with claim 1, wherein

the element vector formation unit sets an arbitrary scanning segment as a first scanning point and a scanning point which is continuous to the first scanning point in time series as a second scanning point so as to form a first element vector;

when a length of the first element vector formed with the first scanning point and the second scanning point is longer than the first predetermined length, the element vector formation unit forms another element vector with the first scanning point and another scanning point which is not continuous to the first scanning point in time series as a new second scanning point;

the element vector formation unit further sets a scanning point which is continuous to the second scanning point in time series as a third scanning point so as to form element vectors; and

when a deflection of a second element vector which is formed by the second scanning point as a start point and the third scanning point as an end point with respect to a first element vector which is formed by the first scanning point as a start point and the second scanning point as an end point is larger than the first predetermined angle, the element vector formation unit excludes the third scanning point and forms an element vector with the second scanning vector and another scanning point which is not continuous to the second scanning point in time series as a new third scanning point.

7. The autonomous vehicle in accordance with claim 1, wherein

when one scanning segment vector is formed by the scanning segment formation unit, the scanning segment vector formation unit attempts to form a new scanning segment vector using scanning points which are not used for forming the scanning segment vector among a plurality of the scanning points.

8. The autonomous vehicle in accordance with claim 7, wherein

when more than one scanning segment vectors are formed, an angle of a second scanning segment vector against another first scanning segment vector is equal to or smaller than a predetermined angle, and a distance from an end point of the first scanning segment vector and a start point of the second scanning segment vector is equal to or shorter than a predetermined distance, the scanning segment vector formation unit forms a new scanning segment vector by composition of the first scanning segment vector and the second scanning segment vector with composing a vector formed with the end point of the first scanning segment vector as a start point and the start point of the second scanning segment vector as an end point.

9. The autonomous vehicle in accordance with claim 1, wherein

the scanning segment vector formation unit stores positional coordinates of scanning points which contribute to form the scanning segment vector;

and

when a segment defined by a start point and an end point of the scanning segment vector is equal to or longer than the second predetermined length, the obstacle recognition unit applies least square method to the stored positional coordinates of the scanning points so as to calculate a segment which is most fining to the scanning points which contribute to form the scanning segment vector, and recognizes that the segments represents a planar obstacle.

10. The autonomous vehicle in accordance with claim 1, wherein

the element vector formation unit forms a first group of element vectors with a first scanning point as a start point and a second scanning point as an end point, wherein an arbitrary scanning point is set as the first scanning point and another scanning point continuous to the first scanning point in time series is set as the second scanning point;

the element vector formation unit further forms a second group of element vectors with a first scanning point as a start point and a second scanning point as an end point, wherein an arbitrary scanning point as the first scanning point and another scanning point continuous to the first scanning point in time series as the second scanning point when a length of the element vector is equal to or shorter than the first predetermined length, or scanning point approximate to but not continuous to the first scanning point in time series as the second scanning point when a length of the element vector is longer than the first predetermined length;

the element vector selection unit selects a plurality of continuous element vectors from the first group of element vectors and selects a plurality of continuous element vectors from the second group of element vectors;

the scanning segment vector formation unit forms a first group of scanning segments by composition of a plurality of the element vectors selected from the first group of element vectors, and forms a second group of scanning segments by composition of a plurality of the element vectors selected from the second group of element vectors, and subtracts element vectors which form the first group of scanning segments from element vectors which form the second group of scanning segments, so that a third group of scanning segment vectors is formed with remained element vectors; and

the obstacle recognition unit compares a segment defined by a start point and an end point of a scanning segment vector belonging to the third group of the scanning segment vectors with the second predetermined length, and when the length of the segment is equal to or longer than the second predetermined length, it recognizes that a planar obstacle having apertures exists along the scanning segment vector belonging the third group of the scanning segment vectors.

11. The autonomous vehicle in accordance with claim 1 further comprising:

a memory which previously memorizes data of map segments which are an aggregation of segments of the planar obstacles existing in a map of an operation area of the autonomous vehicle; and

wherein

the obstacle recognition unit further serves as a segment collation unit, which collates the scanning segment with map segments, specifies positions of the planar obstacles on the map and further specifies a self location of the autonomous vehicle on the map.

12. The autonomous vehicle in accordance with claim 11, wherein

the self location identification unit specifies the self location of the autonomous vehicle on the map of the operation area thereof based on the positions of the planar obstacles on the map, and distances and directions to the planar obstacles from an origin on the autonomous vehicle.

13. A planar object recognition method comprising:

a scanning point acquisition step for scanning a predetermined space at a constant angle or a constant interval with using an electromagnetic wave or an acoustic wave, receiving reflected waves from objects existed in the horizontal plane, and acquiring coordinates of a plurality of scanning points from which the electromagnetic wave or the acoustic wave is reflected;

an element vector forming step forming an element vector with respect to two scanning points selected among the plurality of scanning points so that one scanning point acquired earlier in time series by the scanning point acquisition step is used as a start point of the element vector and another scanning point acquired later is used as an end point of the element vector;

an element vector selecting step selecting a plurality of element vectors which are continued in time series of order of formation by the element vector forming step, length of each element vector being equal to or shorter than a first predetermined length, a deflection angle of an element vector with respect to another continuing element vector being equal to or smaller than a first predetermined angle, and an integrated value of the deflection angles being equal to or smaller than a second predetermined angle;

a scanning segment vector forming step forming one scanning segment vector by composing the selected continuing element vectors; and

an obstacle recognizing step comparing a segment defined by a start point and an end point of the scanning segment vector with a second predetermined length, and recognizing that a planar obstacle exists along the scanning segment vector when the segment is equal to or longer than the second predetermined length.

14. The planar object recognition method with claim 13, wherein

the element vector formation step forms an element vector using only scanning points within a predetermined distance from an arbitrary origin.

15. The planar object recognition method in accordance with claim 13, wherein

the element vector formation step sets an arbitrary scanning segment as a first scanning point and a scanning point which is continuous to the first scanning point in time series as a second scanning point so as to form an element vector;

and

when a length of the element vector formed with the first scanning point and the second scanning point is longer than the first predetermined length, the element vector formation step forms another element vector with the first scanning point and another scanning point which is not continuous to the first scanning point in time series as a new second scanning point.

16. The planar object recognition method in accordance with claim 15, wherein

when no element vector having a length equal to or shorter than the first predetermined length can be formed with respect to the arbitrary scanning point although attempt to form the element vectors predetermined times, the element vector formation step sets another scanning point continuous to the arbitrary scanning point in time series as a new first scanning point and attempts to form an element vector with respect to the new first scanning point.

17. The planar object recognition method in accordance with claim 13, wherein

the element vector formation step sets an arbitrary scanning segment as a first scanning point, a scanning point which is continuous to the first scanning point in time series as a second scanning point, and a scanning point which is continuous to the second scanning point in time series as a third scanning point so as to form element vectors;

and

when a deflection of a second element vector which is formed by the second scanning point as a start point and the third scanning point as an end point with respect to a first element vector which is formed by the first scanning point as a start point and the second scanning point as an end point is larger than the first predetermined angle, the element vector formation step excludes the third scanning point and forms an element vector with the second scanning vector and another scanning point which is not continuous to the second scanning point in time series as a new third scanning point.

18. The planar object recognition method in accordance with claim 13, wherein

the element vector formation step sets an arbitrary scanning segment as a first scanning point and a scanning point which is continuous to the first scanning point in time series as a second scanning point so as to form a first element vector;

when a length of the first element vector formed with the first scanning point and the second scanning point is longer than the first predetermined length, the element vector formation step forms another element vector with the first scanning point and another scanning point which is not continuous to the first scanning point in time series as a new second scanning point;

the element vector formation step further sets a scanning point which is continuous to the second scanning point in time series as a third scanning point so as to form element vectors; and

when a deflection of a second element vector which is formed by the second scanning point as a start point and the third scanning point as an end point with respect to a first element vector which is formed by the first scanning point as a start point and the second scanning point as an end point is larger than the first predetermined angle, the element vector formation step excludes the third scanning point and forms an element vector with the second scanning vector and another scanning point which is not continuous to the second scanning point in time series as a new third scanning point.

19. The planar object recognition method in accordance with claim 13, wherein

when one scanning segment vector is formed by the scanning segment formation step, the scanning segment vector formation step attempts to form a new scanning segment vector using scanning points which are not used for forming the scanning segment vector among a plurality of the scanning points.

20. The planar object recognition method in accordance with claim 19, wherein

when more than one scanning segment vectors are formed, an angle of a second scanning segment vector against another first scanning segment vector is equal to or smaller than a predetermined angle, and a distance from an end point of the first scanning segment vector and a start point of the second scanning segment vector is equal to or shorter than a predetermined distance, the scanning segment vector formation step forms a new scanning segment vector by composition of the first scanning segment vector and the second scanning segment vector with composing a vector formed with the end point of the first scanning segment vector as a start point and the start point of the second scanning segment vector as an end point.

21. The planar object recognition method in accordance with claim 13, wherein

the scanning segment vector formation step stores positional coordinates of scanning points which contribute to form the scanning segment vector;

and

when a segment defined by a start point and an end point of the scanning segment vector is equal to or longer than the second predetermined length, the obstacle recognition step applies least square method to the stored positional coordinates of the scanning points so as to calculate a segment which is most fitting to the scanning points which contribute to form the scanning segment vector, and recognizes that the segments represents a planar obstacle.

22. The planar object recognition method in accordance with claim 13, wherein

the element vector formation step forms a first group of element vectors with a first scanning point as a start point and a second scanning point as an end point, wherein an arbitrary scanning point is set as the first scanning point and another scanning point continuous to the first scanning point in time series is set as the second scanning point;

the element vector formation step further forms a second group of element vectors with a first scanning point as a start point and a second scanning point as an end point, wherein an arbitrary scanning point as the first scanning point and another scanning point continuous to the first scanning point in time series as the second scanning point when a length of the element vector is equal to or shorter than the first predetermined length, or scanning point approximate to but not continuous to the first scanning point in time series as the second scanning point when a length of the element vector is longer than the first predetermined length;

the element vector selection step selects a plurality of continuous element vectors from the first group of element vectors and selects a plurality of continuous element vectors from the second group of element vectors;

the scanning segment vector formation step forms a first group of scanning segments by composition of a plurality of the element vectors selected from the first group of element vectors, and forms a second group of scanning segments by composition of a plurality of the element vectors selected from the second group of element vectors, and subtracts element vectors which form the first group of scanning segments from element vectors which form the second group of scanning segments, so that a third group of scanning segment vectors is formed with remained element vectors; and

the obstacle recognition step compares a segment defined by a start point and an end point of a scanning segment vector belonging to the third group of the scanning segment vectors with the second predetermined length, and when the length of the segment is equal to or longer than the second predetermined length, it recognizes that a planar obstacle having apertures exists along the scanning segment vector belonging the third group of the scanning segment vectors.