Disclosure of Invention
In view of the above, the invention provides a lane-level electronic map construction method based on information fusion, and a map constructed by using the method can be accurately positioned to each lane, so that reliable guarantee is provided for the driving of vehicles.
The technical scheme for realizing the invention is as follows:
a lane-level electronic map construction method based on information fusion comprises the following specific processes:
firstly, a mobile data acquisition platform acquires a panoramic image, positioning data and a traffic signal position in real time, converts the panoramic image into a panoramic top view based on inverse projection transformation, and fuses the positioning data, the traffic signal position and the panoramic top view; the positioning data is obtained by adopting a differential positioning mode;
and step two, splicing the fused panoramic top views to generate a lane-level electronic map.
Furthermore, the method for acquiring the positioning data of the present invention is as follows: and erecting a differential base station on a platform with a known position, wherein the base station transmits real-time differential information to the mobile data acquisition platform by using a communication module, and the mobile data acquisition platform calculates the accurate positioning data of the mobile data acquisition platform according to the position of the base station and the differential information.
Further, the traffic signal position of the invention is obtained by adopting the following mode: firstly, a mobile data acquisition platform acquires an image of a traffic signal; secondly, marking an area where traffic signals possibly exist in the image by an image sequence detector; and finally, the tracker rejects the false detection area in the marking area to obtain the traffic signal position.
Further, the specific process of image stitching in the second step of the present invention is as follows:
step 201, dividing an image acquisition area passed by a mobile data acquisition platform into a plurality of grids with the same size;
step 202, judging whether the current frame image and the previous frame image correspond to the same grid;
step 203, if yes, splicing the current frame image and the previous frame image together according to the position relationship, otherwise, storing the splicing result of the previous frame image, and judging whether the grid corresponding to the current frame image has a stored image;
if so, splicing the stored image with the current frame image together according to the position relationship, otherwise, establishing a storage area of the grid corresponding to the current frame image, and storing the current frame image in the area;
step 204, processing all the fused panoramic overhead images according to the method of step 202-203 to obtain a spliced image corresponding to each grid;
and step 205, splicing the spliced images corresponding to the multiple grids together to generate the lane-level electronic map.
Further, in step 202 of the present invention, the determination is: and identifying the images by utilizing the position information of the mobile data acquisition and acquisition platform when each image is acquired, and judging according to the identification.
A lane-level electronic map construction method based on information fusion comprises the following specific processes:
firstly, a mobile data acquisition platform acquires a panoramic image, positioning data, a traffic signal position and road boundary information in real time, converts the panoramic image into a panoramic top view based on inverse projection transformation, and fuses the positioning data, the traffic signal position, the road boundary information and the panoramic top view; the positioning data is obtained by adopting a differential positioning mode;
splicing the fused panoramic top views to obtain a base map of the lane-level electronic map;
step three, generating a topological relation of the electronic map according to traffic rules and steering information among lanes, and merging the topological relation with the base map obtained in the step two;
and step four, setting a corresponding attribute table for each lane on the image, and generating a lane-level electronic map suitable for the unmanned ground vehicle.
Further, the road boundary information of the present invention is obtained by the following method: the mobile data acquisition platform acquires surrounding environment point cloud data, and road boundary information is determined through multi-feature Hough transformation.
Furthermore, the attribute table comprises a line data set 'road' attribute, a point data set 'road node' attribute and a point data set 'traffic sign' attribute; wherein,
the line data set road attribute comprises the distance between a lane and a left boundary of the road, the distance between the lane and a right boundary of the road, speed limit information of the lane, steering information of the lane, a merging attribute of the lane and the driving direction of the lane;
the point data set 'road node' attribute comprises whether the road node is an intersection or not and whether the road node is an intersection containing a traffic light or not;
the point data set "traffic sign" attributes include the type and attribute values of the traffic sign.
Advantageous effects
(1) When the electronic map is constructed, the acquired panoramic image is converted into the panoramic top view, and the accurate positioning data obtained by using a differential positioning mode is fused, so that the generated electronic map can be specifically accurate to a lane.
(2) When the high-precision electronic map is generated, the invention provides the method for processing the massive image data by using the grid mode, thereby effectively avoiding the condition that the image data cannot be processed due to overlarge data volume.
(3) The invention creates the attribute table for different geographic objects and provides reliable guarantee for the safe driving of the intelligent vehicle in the structured environment.
Detailed Description
The invention is described in detail below, by way of example, with reference to the accompanying drawings.
The invention provides a lane-level electronic map construction method based on information fusion, which comprises the following specific processes as shown in figure 1:
firstly, a mobile data acquisition platform acquires a panoramic image, positioning data and a traffic signal position in real time, converts the panoramic image into a panoramic top view based on inverse projection transformation, and fuses the positioning data, the traffic signal position and the panoramic top view; the positioning data is obtained by adopting a differential positioning mode;
and step two, splicing the fused panoramic top views to generate a lane-level electronic map.
According to the invention, the acquired panoramic image is converted into the panoramic top view which is used as the base map of the electronic map, so that each lane can be clearly seen by the constructed electronic map; meanwhile, the positioning data fused with the panoramic top view is obtained by adopting a differential positioning mode, and compared with the existing GPS positioning mode of the electronic map, the positioning generated by the invention has high precision.
The preferred way of the mobile data acquisition platform to acquire data in real time in this embodiment is as follows:
collecting panoramic images: panoramic image information is required to be collected to be used as a map base map for constructing a high-precision electronic map. Before acquiring a panoramic image, firstly, a panoramic camera on a mobile data acquisition platform needs to be calibrated through a calibration plate, and then a panoramic top view is obtained based on an inverse projection transformation (IPM) algorithm. In addition, in order to splice different panoramic images during post-processing, the position of the data acquisition platform when the images are acquired needs to be utilized to identify the images, and the position information of the data acquisition platform is marked at the lower right corner of the images in a two-dimensional code mode.
Collecting positioning data: the construction of lane-level electronic maps requires that the positioning data can distinguish different lanes, so the accuracy of the positioning data is at least a decimeter level. Currently, the single-point positioning accuracy of the most widely applied satellite positioning navigation system (such as a GPS) is generally more than a meter level. Therefore, the differential positioning technology is adopted in the embodiment, the differential base station is erected on a platform with a known position, and the base station transmits real-time differential information to the mobile data acquisition platform through the mobile communication module, so that the positioning precision can reach centimeter level.
Collecting the position of a traffic signal: the traffic signal comprises a traffic light and a traffic sign, after the image of the traffic light and the traffic sign is obtained through the monocular camera, firstly, the image sequence detector marks the area in the image where the traffic light and the traffic sign possibly exist, and the marked image is regarded as the noisy observation of target positioning; then, the tracker processes the noisy observation by using a data association method in a multi-target tracking algorithm, extracts a real candidate region from a target from the disordered observation and eliminates a false detection region to obtain the positions of the traffic lights and the traffic signs.
The mobile data acquisition platform also acquires surrounding environment point cloud data through a laser radar, determines road boundary information through multi-feature Hough transformation, and fuses the road boundary information and the panoramic top view.
Fig. 2 shows a schematic diagram of devices for collecting data on the mobile data collection platform.
As shown in fig. 3, the specific process of splicing the fused panoramic top view is as follows:
step 201, dividing the image acquisition area passed by the mobile data acquisition platform into a plurality of grids with the same size, each grid corresponding to a determined range, in this example, one grid with the size of 1620m × 360m (27000 pixels × 6000 pixels), and selecting origin coordinates (x) according to the coordinate range of the data acquisition area0,y0) And at the same time, determining the sequence number (i, j) of each grid, as shown in fig. 4;
step 202, determining the grid corresponding to the current frame image according to the position information identified on the image, and judging whether the serial number of the grid is the same as the serial number of the grid corresponding to the previous frame image, namely judging whether the current frame image and the previous frame image correspond to the same grid;
step 203, splicing the two images together according to the position relationship if the serial numbers are the same, namely corresponding to the same grid, otherwise, storing the splicing result of the previous frame of image, and judging whether the grid corresponding to the current frame of image has a stored image before;
if the stored image exists, the stored image and the current frame image are spliced together according to the position relation, otherwise, a region is newly built in the memory to serve as a storage region of a grid corresponding to the current frame image, and the current frame image is stored in the region;
step 204, processing all the fused panoramic overhead images according to the method of step 202-203 to obtain a plurality of images representing different grids;
and step 205, splicing the images representing different grids together according to the serial numbers of the grids to obtain a base map of the high-precision electronic map.
The invention relates to a lane-level electronic map construction method based on information fusion, which comprises the following specific processes:
firstly, a mobile data acquisition platform acquires a panoramic image, positioning data, a traffic signal position and road boundary information in real time, converts the panoramic image into a panoramic top view based on inverse projection transformation, and fuses the positioning data, the traffic signal position, the road boundary information and the panoramic top view; the positioning data is obtained by adopting a differential positioning mode;
splicing the fused panoramic top views;
step three, generating a topological relation of the electronic map according to traffic rules and steering information among lanes, and fusing the topological relation with the image obtained by splicing in the step two; the topological relation is an important component of the electronic map and is a necessary condition for applying the electronic map to path planning and shortest path analysis.
And step four, setting a corresponding attribute table for each lane on the image according to the characteristics of different geographic objects, and generating a lane-level electronic map suitable for the application of the unmanned ground vehicle.
The specific process of constructing the attribute table for different geographic objects is as follows:
first, a line data set "road" is shown in the attribute table 1.
TABLE 1 line data set "road" attribute
Wherein the Left _ Width and Right _ Width attributes represent distances of the current lane from the Left and Right boundaries. The two attributes give left and right boundaries when the unmanned ground vehicle is locally planned, and play an important role in guiding safe driving of the unmanned ground vehicle, and the attributes are calculated by collected road boundary data. The Speed _ Limit attribute represents the Speed Limit information of the current lane, and driving in the Speed Limit range is one of important criteria of intelligent driving; meanwhile, for the driving safety of the vehicle, the electronic map constructed by the invention also limits the speed of the lanes near the intersection according to the steering information of the corresponding lanes (for example, the speed limit of a straight lane is 30km/h, the speed limit of a left-turn right-turn lane is 15km/h, and the speed limit of a U-turn lane is 10 km/h). The Change _ Direction attribute is steering information of the current lane, wherein 0 is straight, 1 is left turn, 2 is right turn, and 3 is turn around. The if _ CrossLine attribute is whether the current lane allows the merging, wherein 0 is prohibited merging, 1 is allowed merging, and vehicles in some areas of the road (such as the vicinity of an intersection) are not allowed to be merged, so that the addition of the attribute has an important indication effect on the unmanned ground vehicle to drive according to the traffic rules. The Direction attribute indicates the Direction of the current lane and is indicated by the Direction angle of the current lane.
The attribute tables corresponding to the point data sets "road node" and "traffic sign" are shown in table 2 and table 3, respectively.
TABLE 2 Attribute for Point data set "road node
The attributes corresponding to the "road node" mainly include an if _ Intersection and an if _ TrafficLight attribute, and respectively indicate whether the road node is an Intersection and whether the road node is an Intersection containing traffic lights.
Table 3 attributes of the point data set "road sign
The attributes corresponding to the traffic sign are Category and Value, the Category attribute represents the type of the traffic sign (such as speed limit, no-go, etc.), and the Value attribute represents the Value of the corresponding traffic sign (such as 40km/h, the attribute Value is 40).
The invention takes an intelligent vehicle research and development center in the mature city of Jiangsu province as a test field to construct an electronic map to verify the effectiveness of the invention.
(1) Firstly, data required by constructing an electronic map are acquired by using a mobile data acquisition platform. The acquired and processed panoramic image data is shown in fig. 5.
(2) Next, according to steps 201 to 205, a base map of the high-precision electronic map is generated, and the obtained base map is shown in fig. 6.
(3) Finally, a topological relation of the electronic map is generated according to the traffic rules and the steering information between the lanes, and the lane-level electronic map obtained according to the traffic rules reflecting the traffic rules of the urban roads is shown in fig. 7.
In summary, the above description is only a preferred example of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.