Method and apparatus for updating maps

Patent metadata

Field	Value
Publication number	US-10705219-B2
Application number	US-201815876032-A
Country	US
Kind code	B2
Filing date	Jan 19, 2018
Priority date	Apr 17, 2017
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

The present application discloses a method and apparatus for updating a map. An implementation of the method comprises: acquiring a laser point clouds obtained by scanning a surrounding environment and acquiring a periodic pose change of a vehicle in a scanning period; determining an a priori pose of the laser radar at a reference time in the current scanning period based on a known pose of the laser radar in a previous scanning period and the periodic pose change; performing motion compensation on the scanned laser point clouds to form a compensated point cloud frame; generating a partial point cloud characteristic map; matching the partial point cloud characteristic map with a map area obtained in a reference point cloud map, and correcting the a priori pose to obtain an a posteriori pose; and updating a three-dimensional point cloud map of a to-be-constructed area using the compensated point cloud frame.

First claim

What is claimed is:

1. A method for updating a map, the method comprising:
acquiring laser point clouds obtained at each scanning time in a current scanning period in response to a vehicle moving in a to-be-constructed area and using a vehicle-borne laser radar to scan a surrounding environment, and acquiring a periodic pose change of the vehicle, relative to a start time, at an end time in each scanning period, the periodic pose change obtained by a vehicle-borne inertial navigation system of the vehicle through measurement and calculation;
determining an a priori pose of the laser radar at a reference time in the current scanning period based on a known pose of the laser radar at a reference time in a previous scanning period before the current scanning period and a periodic pose change of the current scanning period and/or the previous scanning period;
performing motion compensation on the laser point clouds scanned at the each scanning time in the current scanning period by taking the reference time in the current scanning period as a benchmark to forma compensated point cloud frame of the current scanning period;
generating a partial point cloud characteristic map used for matching using a characteristic point extracted from the compensated point cloud frame;
matching the partial point cloud characteristic map with a map area obtained by performing positioning in a reference point cloud map using a position of the a priori pose, and correcting the a priori pose based on a matching result to obtain an a posteriori pose, the reference point cloud map constructed by using laser point clouds obtained through static scanning by three-dimensional scanners deployed at fixed measurement stations of the to-be-constructed area; and
updating a three-dimensional point cloud map of the to-be-constructed area using the compensated point cloud frame in the current scanning period based on the a posteriori pose of the laser radar at the reference time in the current scanning period,
wherein the method is performed by at least one processor.

2. The method according to claim 1 , the method further comprising:
setting the a posteriori pose of the laser radar at the reference time in the current scanning period as a known pose of the laser radar in the current scanning period to process laser point clouds scanned by the laser radar in a following scanning period.

3. The method according to claim 1 , wherein performing motion compensation on the laser point clouds scanned at the each scanning time in the current scanning period by taking the reference time in the current scanning period as a benchmark to form a compensated point cloud frame of the current scanning period comprises:
determining a pose offset of the pose of the laser radar at the each scanning time in the current scanning period relative to the a priori pose of the laser radar at the reference time in the current scanning period based on the periodic pose change of the current scanning period and/or the previous scanning period; and
performing motion compensation on the corresponding laser point clouds scanned at the scanning time based on the pose offset of the laser radar at the each scanning time in the current period, to generate the compensated point cloud frame of the current scanning period.

4. The method according to claim 3 , wherein determining a pose offset of the pose of the laser radar at the each scanning time in the current scanning period relative to the a priori pose of the laser radar at the reference time in the current scanning period based on the periodic pose change of the current scanning period comprises:
calculating the pose offset of the pose of the laser radar at the each scanning time in the current scanning period relative to the a priori pose of the laser radar at the reference time in the current scanning period by considering the pose change of the laser radar in a single scanning period as a uniform change.

5. The method according to claim 1 , wherein generating a partial point cloud characteristic map used for matching using a characteristic point extracted from the compensated point cloud frame comprises:
extracting characteristic points forming a plane and/or a cylinder from the compensated point cloud frame in the current scanning period and the compensated point cloud frame of at least one scanning period adjacent to the current scanning period, respectively; and
splicing the characteristic points extracted from a plurality of compensated point cloud frames to form the partial point cloud characteristic map.

6. The method according to claim 1 , wherein matching the partial point cloud characteristic map with a map area obtained by performing positioning in a reference point cloud map using a position of the a priori pose, and correcting the a priori pose based on a matching result to obtain an a posteriori pose comprises:
performing an iterative adjustment on the a priori pose of the laser radar at the reference time in the current period to enable the partial point cloud characteristic map after pose adjustment and the map area to reach an optimal matching state; and
correcting the a priori pose using an adjustment amount of the iterative adjustment to obtain the a posteriori pose.

7. The method according to claim 1 , wherein the method further comprises generating the reference point cloud map, and the generating comprises:
measuring spatial coordinates of a three-dimensional scanner deployed at each measurement station of the to-be-constructed area station-by-station in a conductor line controlled measurement mode;
performing matching among laser point clouds obtained by scanning a surrounding environment by each three-dimensional scanner to obtain a pose of the each three-dimensional scanner; and
splicing the laser point clouds scanned by the each three-dimensional scanner based on the spatial coordinates and the pose of the each three-dimensional scanner to generate the reference point cloud map.

8. An apparatus for updating a map, the apparatus comprising:
at least one processor; and
a memory storing instructions, which when executed by the at least one processor, cause the at least one processor to perform operations comprising:
acquiring laser point clouds obtained at each scanning time in a current scanning period in response to a vehicle moving in a to-be-constructed area and using a vehicle-borne laser radar to scan a surrounding environment, and acquiring a periodic pose change of the vehicle, relative to a start time, at an end time in each scanning period, the periodic pose change obtained by a vehicle-borne inertial navigation system of the vehicle through measurement and calculation;
determining an a priori pose of the laser radar at a reference time in the current scanning period based on a known pose of the laser radar at a reference time in a previous scanning period before the current scanning period and a periodic pose change of the current scanning period and/or the previous scanning period;
performing motion compensation on the laser point clouds scanned at the each scanning time in the current scanning period by taking the reference time in the current scanning period as a benchmark to form a compensated point cloud frame of the current scanning period;
generating a partial point cloud characteristic map used for matching using a characteristic point extracted from the compensated point cloud frame;
matching the partial point cloud characteristic map with a map area obtained by performing positioning in a reference point cloud map using a position of the a priori pose, and correcting the a priori pose based on a matching result to obtain an a posteriori pose, the reference point cloud map constructed by using laser point cloud

Assignees

• Baidu online network technology beijing co ltd
• Baidu Online Network Tech Beijng Co Ltd

Inventors

• Yi Shichun
• Wang Cheng
• Yu Li
• Song Shiyu
• Xu Baoqiang

Classifications

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S17/86

  Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders · CPC title

• G01S7/003

  Transmission of data between radar, sonar or lidar systems and remote stations · CPC title

• G01S7/4808

  Evaluating distance, position or velocity data · CPC title

• G01S17/88 Primary

  Lidar systems specially adapted for specific applications · CPC title