Lane detection sensor and navigation system employing the same

Abstract: A lane detection sensor (K1) for detecting opposite lane markers of a road, comprising: an image shooting member (1) for shooting an image of the road ahead of a running motor vehicle; an image data memory (2) for storing data on the image of the road from the image shooting member (1); a contour point extracting member (3) for extracting, by using the data on the image of the road stored in the image data memory (2), contour points corresponding to the lane markers of the road; a curve detecting member (4) for calculating polynomial curves by using the contour points corresponding to the lane markers of the road from the contour point extracting member (3); a Hough transformation limiting member (5) for bounding a region of Hough transformation by using coefficients of the polynomial curves calculated by the curve detecting member (4); a Hough transformation member (6) for performing Hough transformation by using the polynomial curves from the curve detecting member (4) and the region of Hough transformation bounded by the Hough transformation limiting member (5); and a Hough transformation detecting member (7) which obtains a maximum value of accumulators in Hough space so as to detect a curve corresponding to the maximum value of the accumulators.

Description: Background of the Invention The present invention as it is defined in the appended claims generally relates to a navigation system comprising an image shooting means for shooting an image of a road ahead of a running motor vehicle, a contour point extracting means for extracting from data on the image of the road from the image shooting means contour points corresponding to opposite lane markers of the road, a lane detecting means for detecting, by using the contour points from the contour point extracting means, the road on which the motor vehicle is running and the lane markers of lanes of the road, a map data base for storing data on the road on a map, and a GPS (global positioning system) calculating means for estimating current position of the motor vehicle upon reception of electromagnetic wave from a GPS. EP 0697641 A2 representing the closest prior art from which the invention proceeds discloses a lane image processing system for a vehicle to recognize the lane on which the vehicle travels. The system has a CCD camera mounted on the vehicle for viewing a roadway scene ahead of the vehicle to output image data of the roadway scene including the lane on which the vehicle travels. Obstacles such as preceding vehicle are detected and a region for image data processing is determined so as to avoid the position of the obstacle and the lane on which the vehicle travels is recognized based on the processed result. More specifically, lane boundary positions estimated up to a preceding cycle are stored as historical information and in the region Hough transformation is limited in areas determined based on the historical information and the horizon in the roadway scene. A further conventional lane detector sensor is disclosed in, for example, JP-A-5-1 51341 as shown in figure 3. This known lane detection sensor includes an image input means 100 for shooting an image of a road ahead of a running motor vehicle, a preparation means 101 which receives a signal from the image input means 100 so as to extract an edge point, a line adaptation means 102 which sets a window in the vicinity of a linear equation obtained at the time of a previous arithmetic operation and measures coordinates of a plurality of edge points in the set window so as to obtain a plurality of linear equations through linear approximation, a line and vanishing point determining means 104 which estimates x- and y-coordinates of a vanishing point and amounts corresponding to slopes of straight lines passing through the vanishing point on the basis of the obtained linear equations so as to minimize a sum of square of errors among the linear equations and sets these estimated values to a result of this time, an edge point tracing means 103 which extracts, on the basis of a result of the preparation means 101 and a detection result of the linear adaptation means 102, an edge point corresponding to a lane marker, a curve adaptation means 105 which applies a curved equation to the extracted edge point and a smoothing means 106 for smoothing a result of the curve adaptation means 105. In this known lane detection sensor, application of the curved equation is performed by method of least squares and therefore, is readily affected by noises. As a result, it is impossible to detect the lane makers accurately. Moreover, a still further known detection apparatus for detecting a radius of curvature of a road is disclosed in, for example, JP-A-2-115905 (1990) as shown in Fig. 4. This known detection apparatus includes an imaging means 107 for shooting an image of an external environment, a detection means 108 for detecting from the image a target along a route of a running motor vehicle and relative positional relation between the target and the running motor vehicle, a track generating means 109 for generating a track regulated by a predetermined function based on the relative positional relation and a control means 110 for controlling running of the motor vehicle in accordance with the generated track. In this prior art detection apparatus, since the radius of curvature of the road is determined on the basis of the distant landmark, errors of the radius of curvature of the road are large and thus, it is impossible to obtain the radius of curvature of the road accurately. Furthermore, conventionally, a navigation system loaded on a motor vehicle can receive only predetermined map data but cannot receive data available during running of the motor vehicle. In addition, in the conventional navigation system, it has been difficult to guide the motor vehicle accurately when the motor vehicle is running across a plurality of lanes. SUMMARY OF THE INVENTION Accordingly, an essential object of the present invention is to provide, with a view to eliminating the above mentioned disadvantages of prior art, a navigation system in which a unique map can be formulated by measuring width and the number of lanes of a road and can be used as a guide at the time of another running on the road. By detecting position of the lane on which the motor vehicle is running and the number of the lanes, the navigation system of the present invention is capable of guiding the motor vehicle accurately. In order to accomplish this object of the present invention, a navigation system according to the present invention comprises: an image shooting means for shooting an image of a road ahead of a running motor vehicle; a contour point extracting means for extracting from data on the image of the road from the image shooting means, contour points corresponding to opposite lane markers of the road; a lane detecting means for detecting, by using the contour points from the contour point extracting means, the road on which the motor vehicle is running and the lane markers of lanes of the road; a map data base for storing data on the road on a map; a GPS (global positioning system) calculating means for estimating current position of the motor vehicle upon reception of electromagnetic wave from a GPS; a road condition detecting means which obtains width and the number of the lanes from position and shape of the lane markers in the image from the lane detecting means; a road condition storage means for storing, in accordance with the current position of the motor vehicle from the GPS calculating means, the width and the number of the lanes from the road condition detecting means in association with the data on the road on the map of the map data base; and a display means for displaying the current position of the motor vehicle from the GPS calculating means, the data on the road on the map from the map data base and data on the road on which the motor vehicle is running, from the road condition storage means. In the navigation system of the present invention, unique data on the road can be formulated. In case the motor vehicle runs on the same road again, data on the road can be obtained beforehand. In addition, such an effect can be gained that the motor vehicle can be guided to the destination by concrete data. BRIEF DESCRIPTION OF THE DRAWINGS These objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a block diagram of a navigation system according to a first embodiment of the present invention; Fig. 2 is a block diagram of a navigation system according to a second embodiment of the present invention; Fig. 3 is a block diagram of a prior art lane detection sensor (already referred to); and Fig. 4 is a block diagram of a prior art arithmetic unit for calculating a radius of curvature of a road (already referred to). Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows a navigation system M1 according to a first embodiment of the present invention. The navigation system M1 includes an image shooting means 61 for shooting an image of a road ahead of a running motor vehicle, a contour point extracting means 62, a lane detecting means 63, a map data base 64, a GPS calculating means 65 for calculating position of the running motor vehicle, a road condition detecting means 66, a road condition storage means 67 and a display means 68. Hereinafter, operation of the navigation system M1 of the above described arrangement is described. Initially, the image of the road ahead of the running motor vehicle is inputted to the navigation system M1 from the image shooting means 61. In the contour point extracting means 62, an edge is obtained by using the image data of the road from the image shooting means 61 and a threshold value is set from edge intensity of the whole image so as to find edge intensities exceeding initially the threshold value by scanning the image upwardly from a bottom portion of the image and laterally in opposite directions from a center of the image such that the edge intensities are set as contour points of right and left lane markers of the road. In the lane detecting means 63, all lane markers are detected as straight lines from the above mentioned contour points through Hough transformation. In the road condition detecting means 66, the lane of the road is obtained by using the detected lane markers. Meanwhile, from a width between the detected right and left lane markers of the lane on which the motor vehicle is running, a width of the lane is obtained in a global system of coordinates. On the other hand, the number and widths of lanes of the road from the road condition detecting means 66 are stored in the road condition storage means 67 on the basis of map data from the map data base 64 by using data on current position of the motor vehicle from the GPS calculating means 65. In the display means 68, not only the map data from the map data base 64 is displayed on the basis of data on current position of the motor vehicle from the GPS calculating means 65 but the number and widths of the lanes of the road up to a destination are stored in association with the map data and are displayed. Once the motor vehicle equipped with the navigation system M1 has run on one road, the number and widths of lanes of the road are stored in association with the map. Therefore, in case the motor vehicle runs on the same road again, data on the road can be obtained beforehand. Fig. 2 shows a navigation system M2 according to a second embodiment of the present invention. The navigation system M2 includes an image shooting means 71 for shooting an image of a road ahead of a running motor vehicle, a contour point extracting means 72, a lane detecting means 73, a road condition detecting means 74, a map data base 75, a destination input means 76, a running route determining means 77, a GPS calculating means 78 for calculating position of the running motor vehicle, a guide means 79 and a data conveying means 80. Hereinafter, operation of the navigation system M2 of the above described arrangement is described. Initially, the image of the road ahead of the running motor vehicle is inputted to the navigation system M2 from the image shooting means 71. In the contour point extracting means 72, an edge is obtained by using the image data of the road from the image shooting means 71 and a threshold value is set from edge intensity of the whole image so as to find edge intensities exceeding initially the threshold value by scanning the image upwardly from a bottom portion of the image and laterally in opposite directions from a center of the image such that the edge intensities are set as contour points of right and left lane markers of the road. In the lane detecting means 73, all lane markers are detected as straight lines from the above mentioned contour points through Hough transformation. In the road condition detecting means 74, the number of lanes of the road and position of the lane on which the motor vehicle is running are obtained by using the detected lane markers. In the running route determining means 77, a running route of the motor vehicle is obtained from the map data of the map data base 75 and a destination which a driver of the motor vehicle has inputted by operating the running route determining means 77. In the guide means 79, the lane on which the motor vehicle should run is determined by utilizing data on position of the motor vehicle from the GPS calculating means 78, the map data from the map data base 75 based on the data on position of the motor vehicle and the running route up to the destination from the running route determining means 77 and data on lane change is formulated by utilizing the number of the lanes and the position of the lane on which the motor vehicle is running, which are obtained by the road condition detecting means 74. The data conveying means 80 gives to the driver the data on lane change. By recognizing from the road image of the image shooting means 71, position of the lane on which the motor vehicle is running, concrete data for guiding the motor vehicle to the running route can be supplied to the driver by the navigation system M2.

Claims: A navigation system (M1) comprising: an image shooting means (61) for shooting an image of a road ahead of a running motor vehicle; a contour point extracting means (62) for extracting from data on the image of the road from the image shooting means (61), contour points corresponding to opposite lane markers of the road; a lane detecting means (63) for detecting, by using the contour points from the contour point extracting means (62), the road on which the motor vehicle is running and the lane markers of lanes of the road; a map data base (64) for storing data on the road on a map; a GPS (global positioning system) calculating means (65) for estimating current position of the motor vehicle upon reception of electromagnetic wave from a GPS; and a display means (68) for displaying the current position of the motor vehicle from the GPS calculating means (65) and the data on the road on the map from the map data base (64); characterized in that a road condition detecting means (66) is provided for obtaining width and the number of the lanes from position and shape of the lane markers in the image from the lane detecting means (63); a road condition storage means (67) is provided for storing, in accordance with the current position of the motor vehicle from the GPS calculating means (65), the width and the number of the lanes from the road condition detecting means (66) in association with the data on the road on the map of the map base (64); and said display means (68) additionally displays the data on the road on which the motor vehicle is running, from the road condition storage means (67). A navigation system (M2) comprising: an image shooting means (71) for shooting an image of a road ahead of a running motor vehicle; a contour point extracting means (72) for extracting from data on the image of the road from the image shooting means (71), contour points corresponding to opposite lane markers of the road; a lane detecting means (73) for detecting, by using the contour points from the contour point extracting means (72), the road on which the motor vehicle is running and the lane markers of lanes of the road; a map data base (75) for storing data on the road on a map; a destination input means (76) for inputting a destination of the motor vehicle; a running route determining means (77) for determining a running route of the motor vehicle from the destination of the destination input means (76) and the data on the road on the map of the map data base (75); and a GPS (global positioning system) calculating means (78) for estimating current position of the motor vehicle upon reception of electromagnetic wave from a GPS; characterized by a road condition detecting means (74) which obtains the number of the lanes and data on a lane having the motor vehicle running thereon, from position and shape of the lane markers in the image from the lane detecting means (73); a guide means (79) which obtains, by using the data on the road on the map from the map data base (75), the running route from the running route determining means (77), the estimated current position of the motor vehicle from the GPS calculating means (78) and the number of the lanes and the data on the lane having the motor vehicle running thereon from the road condition detecting means (74), a lane to be taken so as to determine shifting direction of the motor vehicle and position of the lane to be taken; and a data conveying means (80) for informing a driver of the motor vehicle of data on the shifting direction of the motor vehicle and the position of the lane to be taken, from the guide means (79).

Inventors: IISAKA ATSUSHI, KANEKO MAMORU, YASUI NOBUHIKO, IISAKA, ATSUSHI, KANEKO, MAMORU, YASUI, NOBUHIKO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1997
Main classification: G08G1
IPC codes: G08G1, G01B11, G06T7, G05D1, G06T1, B60W30, G01C21, G09B29