CN114791596A - Method and system for calibrating external parameters of waterborne multi-line laser radar - Google Patents
Method and system for calibrating external parameters of waterborne multi-line laser radar Download PDFInfo
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Abstract
The invention relates to a method and a system for calibrating external parameters of an overwater multiline laser radar, and belongs to the field of external parameter calibration of laser radars. The method comprises the following steps: acquiring hull pose data and buoy point cloud data of the unmanned ship; converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference; determining a conversion relation from a laser radar coordinate system to a map coordinate system according to the buoy point cloud data; determining external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the ship body pose data; and completing the calibration of the laser radar according to the external parameters of the laser radar. The method adopts the conical buoy, which is beneficial to increasing the number of point cloud data of the laser radar on water, and the conical buoy can provide more stable and reliable characteristics for the point cloud data matching body obtained by the laser radar, and improve the precision of point cloud data matching, thereby being beneficial to improving the precision of external reference calibration of the laser radar.
Description
Technical Field
The invention relates to the field of laser radar external reference calibration, in particular to a method and a system for calibrating an external reference of an overwater multiline laser radar.
Background
When the sensing system based on the laser radar works, the relative position relation between the laser radar and the unmanned ship, namely external parameters (the external parameters comprise a rotation parameter and a translation parameter; the rotation parameter comprises a roll angle roll, a pitch angle pitch and a yaw angle yaw; and the translation parameter comprises x, y and z). The laser radar external reference calibration of the unmanned ship needs to be carried out on the water surface, but at present, no laser radar calibration method aiming at the water surface environment of the unmanned ship exists, and the laser radar external reference calibration of the unmanned ship is generally calibrated by referring to a calibration method of a ground unmanned vehicle.
At present, many laser radar external reference calibration methods for ground vehicles exist, for example, a multi-line laser radar external reference calibration method on an unmanned vehicle by means of a marker, a specific calibration target needs to be arranged in a calibration environment, three-dimensional coordinates of a calibration point under a vehicle coordinate system and a radar coordinate system are respectively obtained, and parameter calculation is performed on the three-dimensional coordinates based on a preset conversion formula to obtain a parameter calculation result. And determining external parameters of the multi-line laser radar based on the parameter calculation result. The method needs the vehicle to be calibrated in a fixed scene, and needs to arrange more than 12 calibration targets, so the process is very complicated. The method for calibrating the external reference of the multi-line laser radar on the unmanned vehicle without the marker is an optimization process essentially, and the main core is to construct an objective function to be optimized. The method comprises the steps of acquiring motion increment between two frames of laser radar data in a vehicle coordinate system in the vehicle motion process, and simultaneously acquiring motion estimation in the laser radar coordinate system in a laser radar data matching mode. The rotation of a laser radar coordinate system and the rotation of a vehicle coordinate system can be converted into the same coordinate system through external parameters of the laser radar, a homogeneous linear overdetermined equation set is constructed, and the least square problem is solved to obtain the external parameters.
In the conventional laser radar external reference calibration of the unmanned ship, the unmanned ship needs to perform autonomous or remote control movement on the water surface along a specific track, point cloud data of the surrounding environment is acquired in the movement process, and pose data of the unmanned ship is recorded in real time. After enough data are collected, calculation and solution can be carried out through the data to obtain the external parameters of the laser radar. The solving and calculating process is essentially an optimization process, and the main core is to construct an objective function to be optimized. And obtaining the motion increment between two frames of laser radar data under the coordinate system of the unmanned ship, and obtaining the motion estimation under the coordinate system of the laser radar by using a laser radar data matching mode. And converting the rotation of a laser radar coordinate system and the rotation of the unmanned ship coordinate system into the same coordinate system through external parameters of the laser radar, constructing a homogeneous linear overdetermined equation set, and solving a least square problem to obtain the external parameters.
By analyzing the processes, it can be seen that in the process of optimally solving the external parameters of the laser radar, the constraint of the objective function has two items, wherein one item is the motion estimation by utilizing the matching principle between two frames of point clouds. Therefore, the matching precision of the point cloud can influence the calibration precision of the laser radar external parameter. When the laser radar calibration is carried out in the water environment, the dielectric constant of water is very large (83.83 at 10 ℃), the absorption rate of electromagnetic waves is very high, and the intensity of the echo of laser emitted to the water surface is very low. Therefore, only a small amount of point cloud can be obtained by the laser radar on the open water. The point clouds cannot generate enough features, so that two frames of point clouds cannot be effectively matched, the matching precision is reduced, and the external reference calibration precision of the laser radar is seriously influenced.
Another constraint is the motion increment of the drone coordinate system between two frames of lidar data. Because the unmanned ship performs plane motion on the water surface when running, the rolling angle roll, the pitch angle pitch and the variation of the height z of the unmanned ship are small, and the unmanned ship cannot be excited sufficiently, and cannot acquire enough effective data. Therefore, the calibration accuracy of the roll angle roll, the pitch angle pitch and the height z in the external reference of the laser radar can be affected.
Disclosure of Invention
The invention aims to provide a method and a system for calibrating external parameters of a water multi-line laser radar, and aims to solve the problem that the calibration precision of the laser radar external parameter calibration method in the prior art is low.
In order to achieve the purpose, the invention provides the following scheme:
an external reference calibration method for an overwater multiline laser radar comprises the following steps:
acquiring hull pose data and buoy point cloud data of the unmanned ship;
converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference;
determining a conversion relation from a laser radar coordinate system to a map coordinate system according to the buoy point cloud data;
determining external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the position and attitude data of the ship body; the external parameters of the laser radar comprise a rotation parameter and a translation parameter; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters comprise translation parameters in the x direction, translation parameters in the y direction and translation parameters in the z direction;
and completing the calibration of the laser radar according to the external parameters of the laser radar.
Optionally, the acquiring the hull pose data of the unmanned ship and the point cloud data of the laser radar further includes:
and arranging a laser radar external reference calibration scene.
Optionally, the arrangement of the laser radar external reference calibration scene specifically includes:
arranging 3 conical buoys within a preset range from the hull of the unmanned ship; the buoys are identical in shape, weight, material, and volume.
Optionally, the acquiring of the hull pose data and the buoy point cloud data of the unmanned ship specifically includes:
and in a preset time, enabling the unmanned ship to do 8-shaped motion around the buoy and acquiring the ship body position data and the buoy point cloud data of the unmanned ship through a laser radar on the unmanned ship.
Optionally, after acquiring the hull pose data and the buoy point cloud data of the unmanned ship, the method further includes:
and preprocessing the hull position data and the buoy point cloud data of the unmanned ship to obtain preprocessed hull position data and preprocessed buoy point cloud data.
Optionally, the preprocessing the hull pose data of the unmanned ship and the buoy point cloud data specifically includes:
carrying out time synchronization processing on the hull pose data of the unmanned ship and the buoy point cloud data;
filtering the buoy point cloud data to obtain filtered buoy point cloud data;
and forming a data queue by the filtered buoy point cloud data and the hull pose data of the unmanned ship.
Optionally, the determining a conversion relationship from a laser radar coordinate system to a map coordinate system according to the buoy point cloud data specifically includes:
according to the formula
Determining the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z (ii) a Wherein, x is [ roll 'pitch' t z ] T Roll 'is the conversion relation of the roll angle, pitch' is the conversion relation of the pitch angle, t z For translation conversion relation from laser radar coordinate system to map coordinate system；
The height of the ith point cloud data in a map coordinate system is obtained; and L is a set of the filtered buoy point cloud data, and i is the ith point cloud data.
Optionally, the determining external parameters of the lidar according to the conversion relationship from the lidar coordinate system to the map coordinate system and the ship body pose data specifically includes:
according to the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z And the preprocessed ship body pose data by using a formula
Determining a roll angle roll, a pitch angle pitch and a translation parameter z in the z direction; wherein, the first and the second end of the pipe are connected with each other,
converting the relation from the laser radar to a map coordinate system;
is a laser radar external parameter matrix;
the preprocessed ship body pose data are obtained;
substituting the roll angle roll, the pitch angle pitch and the translation parameter z in the z direction into the laser radar external parameter matrix, converting the three-dimensional external parameter calibration into two-dimensional plane calibration, and determining the yaw angle yaw, the translation parameter x in the x direction and the translation parameter y in the y direction.
An external reference calibration system for a water multiline laser radar comprises:
the data acquisition module is used for acquiring the hull pose data and the buoy point cloud data of the unmanned ship;
the data conversion module is used for converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference;
the conversion relation determining module is used for determining the conversion relation from the laser radar coordinate system to the map coordinate system according to the buoy point cloud data;
the external parameter determining module is used for determining the external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the ship body pose data; the external parameters of the laser radar comprise rotation parameters and translation parameters; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters comprise translation parameters in the x direction, translation parameters in the y direction and translation parameters in the z direction;
and the calibration module is used for completing the calibration of the laser radar according to the external parameters of the laser radar.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention achieves the purpose of increasing the point cloud characteristics identified by the laser radar by adopting a mode of arranging the conical buoy on the water surface. And meanwhile, when calculating and solving, adding a constraint item based on the water surface environment characteristics, decoupling the laser radar external parameter calibration process, firstly calculating roll, pitch and z by using the water surface characteristics, converting three-dimensional calibration into two-dimensional calibration after the external roll, pitch and z are determined, and then calculating yaw, x and y according to point cloud matching and hull motion constraint. Therefore, the laser radar calibration is completed and the external reference calibration precision of the laser radar is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for calibrating external parameters of a water multi-line laser radar provided by the invention;
FIG. 2 is a layout diagram of a calibration scene of the water surface lidar provided by the invention;
FIG. 3 is a flow chart of the water surface lidar calibration data acquisition provided by the present invention;
FIG. 4 is a flow chart of filtering buoy point cloud data according to the present invention;
FIG. 5 is a flowchart of a method for calibrating an external reference of an overwater multiline laser radar according to an embodiment of the present invention;
fig. 6 is a structural diagram of an external reference calibration system for a water multi-line laser radar provided by the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention aims to provide a method and a system for calibrating external parameters of a water multi-line laser radar, and aims to solve the problem that the calibration precision of the laser radar external parameter calibration method in the prior art is low.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a flowchart of a method for calibrating an external reference of a waterborne multiline lidar provided by the present invention, fig. 5 is a flowchart of a method for calibrating an external reference of a waterborne multiline lidar in an embodiment of the present invention, and as shown in fig. 1 and 5, a method for calibrating an external reference of a waterborne multiline lidar includes:
step 101: and acquiring the position and pose data of the hull of the unmanned ship and the point cloud data of the buoy.
In a specific embodiment, the acquiring of the hull pose data of the unmanned ship and the point cloud data of the laser radar further includes:
and arranging a laser radar external reference calibration scene.
In a specific embodiment, the arranging of the lidar external reference calibration scene specifically includes:
arranging 3 conical buoys within a preset range from the hull of the unmanned ship; the buoys are identical in shape, weight, material, and volume.
In practical applications, a lidar external reference calibration scenario is first deployed, as shown in fig. 2, with three conical buoys deployed 50-80 meters around the hull (depending on the lidar parameters used). The shape, weight, material and volume of the conical buoy used must be consistent to ensure that the height of the part of the buoy exposed to the water surface is the same. Because the reflectivity of water to laser is low, and the reflectivity of the buoy to the laser is high, the laser radar can detect the point cloud of the part of the buoy exposed out of the water surface.
In a specific embodiment, the acquiring of the hull pose data and the buoy point cloud data of the unmanned ship specifically includes:
and in a preset time, enabling the unmanned ship to move around the buoy in an 8-shaped manner, and acquiring the ship body pose data and the buoy point cloud data of the unmanned ship through a laser radar on the unmanned ship.
In practical applications, after the calibration scene is arranged, data acquisition is performed, as shown in fig. 3. And (3) enabling the unmanned ship to do infinity motion at a low speed (less than 1.5 m/s) within the range of 3 buoys for 2 minutes to acquire hull pose data and buoy point cloud data required by calibration.
In one embodiment, after acquiring the hull pose data and the buoy point cloud data of the unmanned ship, the method further comprises the following steps:
and preprocessing the hull pose data and the buoy point cloud data of the unmanned ship to obtain preprocessed hull pose data and preprocessed buoy point cloud data.
In a specific embodiment, the preprocessing the hull pose data and the buoy point cloud data of the unmanned ship specifically includes:
and carrying out time synchronization processing on the hull pose data of the unmanned ship and the buoy point cloud data.
And filtering the buoy point cloud data to obtain filtered buoy point cloud data.
And forming a data queue by the filtered buoy point cloud data and the hull pose data of the unmanned ship.
In practical application, data synchronization is firstly carried out, buoy point cloud data and unmanned ship body pose data are subjected to time synchronization, then filtering processing is carried out on the buoy point cloud data, a filtering flow chart of the buoy point cloud data is shown in fig. 4, the reflectivity of water to laser is low, but impurities are inevitable in the water, and the impurities can reflect the laser sometimes to generate some point cloud impurities. The water bloom can also reflect laser to generate point cloud due to waves generated by system movement, the laser reflection intensity of the point cloud data is low, and the point cloud clutter can be filtered by setting a threshold value for the point cloud echo intensity. In addition, point clouds which are too close (any value of x \ y \ z is less than 10 meters) or too far (any value of x \ y \ z is more than 150 meters) to the ship body are not needed and can be removed.
And forming a one-to-one corresponding data queue by using the filtered buoy point cloud data and the ship body pose data which are subjected to time synchronization.
Step 102: and converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference.
Roll, pitch, z are calculated according to the constraints of the water surface environment.
The horizontal plane is taken as a reference, namely a map coordinate system. Converting the point cloud into a map coordinate system:
in the above formula, yaw ', pitch ' and roll ' are the rotation conversion relation from the laser radar coordinate system to the map coordinate system, t x 、t y 、t z For the translation transformation relationship from the lidar coordinate system to the map coordinate system, [ X ] m Y m Z m ] T As coordinates of the buoy point cloud data in the map coordinate system, [ X ] l Y l Z l ] T Coordinates of the buoy point cloud data in a laser radar coordinate system. The height of the buoy point cloud projected to the map coordinate system is as follows:
Z m ＝-sin(pitch')*X l +cos(pitch')sin(roll')*Y l +cos(pitch')cos(roll')*Z l +t z
from the above formula, the height of the original point cloud projected to the map coordinates is only the sum of pitch ', roll', and t z It is relevant. According to the characteristics of the water surface environment, the point clouds at the bottoms of 3 buoys are converted to map coordinates and are all above the water surface, and the point cloud at the bottommost of the 3 buoys is just on the horizontal plane, namely the height Z m ＝0。
Step 103: and determining the conversion relation from the laser radar coordinate system to the map coordinate system according to the buoy point cloud data.
In one embodiment, the determining a conversion relationship from a laser radar coordinate system to a map coordinate system according to the buoy point cloud data specifically includes:
according to the formula
Determining the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z (ii) a Wherein, x is [ roll 'pitch' t z ] T Roll 'is the conversion relation of the roll angle, pitch' is the conversion relation of the pitch angle, t z The translation transformation relation from the laser radar coordinate system to the map coordinate system is obtained;
the height of the ith point cloud data in a map coordinate system is obtained; and L is a set of the filtered buoy point cloud data, and i is the ith point cloud data.
In practical application, an optimization problem is constructed, and for the point cloud of 3 buoys, the point cloud is converted into a map coordinate system, and the height Z of all the points is calculated m Summing
Optimizing x ═[roll'pitch't z ] T To make
Minimum, and arbitrary Z m ≥0：
Solving the optimization problem to obtain roll ', pitch' and t from the laser radar to the map coordinate system z 。
Step 104: determining external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the ship body pose data; the external parameters of the laser radar comprise a rotation parameter and a translation parameter; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters include a translation parameter in the x-direction, a translation parameter in the y-direction, and a translation parameter in the z-direction.
In a specific embodiment, the determining external parameters of the lidar according to the conversion relationship from the lidar coordinate system to the map coordinate system and the ship body pose data specifically includes:
according to the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z And the preprocessed ship body position and attitude data are processed by a formula
Determining a roll angle roll, a pitch angle pitch and a translation parameter z in the z direction; wherein the content of the first and second substances,
converting the relation from the laser radar to a map coordinate system;
is a laser radar external parameter matrix;
is after said pretreatmentAnd (5) ship body pose data.
Substituting the roll angle roll, the pitch angle pitch and the translation parameter z in the z direction into the laser radar external parameter matrix, converting the three-dimensional external parameter calibration into two-dimensional plane calibration, and determining the yaw angle yaw, the translation parameter x in the x direction and the translation parameter y in the y direction.
In practical application, solving the optimization problem results in roll ', pitch', t z Then, the ship body coordinate is converted into a map coordinate to obtain a rotation translation matrix, namely ship body pose data
Have been obtained by the above-described data acquisition steps. So that according to the formula,
can calculate the external parameter matrix of the laser radar relative to the ship body
Roll, pitch, z in (1). The calculation process is as follows:
According to the formula
Comprises the following steps:
the roll, pitch, z can be solved from the above equation.
Since roll, pitch and z in the lidar external references are already available. The external parameters to be calculated are also the translation parameters X, Y of the vessel in the X-Y plane, and the rotation angle yaw around the Z-axis. By substituting the roll, pitch and z parameters obtained in the above way into the laser radar external reference matrix, the three-dimensional external reference calibration can be converted into two-dimensional plane calibration for obtaining the yaw, x and y parameters. The solving process of the two-dimensional plane parameters yaw, x, and y is as follows.
Firstly, the point clouds of three buoys are projected to a horizontal plane, namely the height Z of all the buoy point clouds m ＝0。
On a two-dimensional plane, the unmanned ship has the following equation at any two positions b1 and b2,
wherein
To coordinate point p under the lidar at drone position b1,
to determine the coordinates of point p under the lidar at position b2 of the drone,
is a laser radar external parameter matrix [ yaw, x, y]，
For the hull pose data when the hull is at position b1,
is the hull pose data for the hull at position b 2.
The above equation is converted:
can be simplified into
Wherein
As laser radar external reference matrix [ yaw, x, y ] to be solved]，
For laser radar relative between two different positionsPosition and pose [ yaw l 、x l 、y l ]The method can be obtained through a laser radar two-frame point cloud matching algorithm.
For changing the pose of the hull at two different positions [ yaw b 、x b 、y b ]Obtained by a data acquisition step;
when the unmanned ship is at the position b1, the laser radar reaches the p-point position-posture conversion relation;
the pose transformation relation between the laser radar and the map when the unmanned ship is at the position b 1;
is composed of
The inverse matrix of (c). Selecting more than four data from the collected calibration data to obtain more than three data
And
forming an over-determined equation set, and solving by a least square method to obtain [ yaw, x, y]。
Step 105: and completing the calibration of the laser radar according to the external parameters of the laser radar. In step 104, all the six external parameters [ yaw, roll, pitch, x, y, z ] of the laser radar are obtained, and the calibration is completed.
The invention adopts a method of arranging buoys to establish a calibration environment on the external reference water of the laser radar. In the data acquisition process, the ship is enabled to move in a buoy range in a 8-shaped mode, and the time is limited to be within 2 minutes. A decoupling mode is adopted to calculate laser radar external parameter data, and three-dimensional calibration is converted into two-dimensional calibration. And solving and calculating roll, pitch and z in the laser radar external parameters by utilizing the water surface environment constraint. The conical buoy is used, and the problem that the reflectivity of the circular buoy to the laser radar is low is solved. 3 buoys are used, so that the number of buoys is small, the buoys are convenient to arrange and recover, and the calibration efficiency is improved.
Fig. 6 is a structural diagram of an external reference calibration system for a multi-line lidar according to the present invention, as shown in fig. 6, the system includes:
the data acquisition module 601 is configured to acquire hull pose data and buoy point cloud data of the unmanned ship.
And a data conversion module 602, configured to convert the buoy point cloud data into buoy point cloud data in a map coordinate system based on a horizontal plane.
And a conversion relation determining module 603, configured to determine a conversion relation from the laser radar coordinate system to the map coordinate system according to the buoy point cloud data.
And the external parameter determining module 604 is configured to determine external parameters of the laser radar according to the conversion relationship from the laser radar coordinate system to the map coordinate system and the ship body pose data. The external parameters of the laser radar comprise rotation parameters and translation parameters; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters include a translation parameter in the x-direction, a translation parameter in the y-direction, and a translation parameter in the z-direction.
And a calibration module 605, configured to complete calibration of the laser radar according to the external parameter of the laser radar.
The invention adopts a buoy arrangement mode to establish the water calibration environment of the unmanned ship. The mode that adopts conical buoy helps increasing the quantity of laser radar point cloud on water to conical buoy can provide more reliable and stable characteristic for laser radar point cloud matching body, improves the precision that the point cloud matches. The precision of the point cloud matching during motion estimation is improved. Therefore, the accuracy of the laser radar external parameter calibration is improved.
The present invention uses a decoupled data computation method that utilizes surface environmental characteristics. Firstly, according to the characteristic that laser is not reflected by the water surface, point cloud data of the obtained conical buoy are all higher than the water surface, and the point cloud at the bottom of the conical buoy is just above the horizontal plane, namely the height z is 0. Through the environmental characteristics, the three parameters of roll, pitch and z are decoupled, and an optimized objective function is constructed and solved aiming at the three parameters. The problem of roll, pitch, three parameters of z because unmanned ship is plane motion, can't fully encourage to mark the precision low is solved.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principle and the embodiment of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.
Claims (9)
1. A method for calibrating external parameters of a water multiline laser radar is characterized by comprising the following steps:
acquiring the position and pose data of a hull of the unmanned ship and the point cloud data of a buoy;
converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference;
determining a conversion relation from a laser radar coordinate system to a map coordinate system according to the buoy point cloud data;
determining external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the position and attitude data of the ship body; the external parameters of the laser radar comprise a rotation parameter and a translation parameter; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters comprise translation parameters in the x direction, translation parameters in the y direction and translation parameters in the z direction;
and completing the calibration of the laser radar according to the external parameters of the laser radar.
2. The method for calibrating the external parameters of the waterborne multiline laser radar according to claim 1, wherein the acquiring of the hull pose data of the unmanned ship and the point cloud data of the laser radar further comprises:
and arranging a laser radar external reference calibration scene.
3. The method for calibrating the external parameters of the overwater multiline lidar according to claim 2, wherein the arrangement of the external parameter calibration scene of the lidar specifically comprises:
arranging 3 conical buoys within a preset range from the hull of the unmanned ship; the buoys are identical in shape, weight, material and volume.
4. The method for calibrating the external reference of the aquatic multiline lidar according to claim 3, wherein the acquiring of the hull pose data and the buoy point cloud data of the unmanned ship specifically comprises:
and in a preset time, enabling the unmanned ship to move around the buoy in an 8-shaped manner, and acquiring the ship body pose data and the buoy point cloud data of the unmanned ship through a laser radar on the unmanned ship.
5. The method for calibrating the external reference of the aquatic multiline lidar according to claim 1, wherein after acquiring the hull pose data and the buoy point cloud data of the unmanned ship, the method further comprises:
and preprocessing the hull pose data and the buoy point cloud data of the unmanned ship to obtain preprocessed hull pose data and preprocessed buoy point cloud data.
6. The method for calibrating the external reference of the waterborne multiline lidar according to claim 5, wherein the preprocessing of the hull pose data and the buoy point cloud data of the unmanned ship specifically comprises:
carrying out time synchronization processing on the hull pose data of the unmanned ship and the buoy point cloud data;
filtering the buoy point cloud data to obtain filtered buoy point cloud data;
and forming a data queue by the filtered buoy point cloud data and the hull pose data of the unmanned ship.
7. The method for calibrating the external reference of the aquatic multiline lidar according to claim 6, wherein the determining of the conversion relationship from the lidar coordinate system to the map coordinate system according to the buoy point cloud data specifically comprises:
according to the formula
Determining the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z (ii) a Wherein, x is [ roll 'pitch' t z ] T Roll 'is the conversion relation of the roll angle, pitch' is the conversion relation of the pitch angle, t z The translation transformation relation from the laser radar coordinate system to the map coordinate system is obtained;
the height of the ith point cloud data in a map coordinate system is obtained; l is a set of the filtered buoy point cloud data, and i is ith point cloud data.
8. The method for calibrating the external parameters of the overwater multiline laser radar according to claim 7, wherein the determining of the external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the position and pose data of the ship body specifically comprises:
according to the conversion relationship roll ', pitch' and t from the laser radar coordinate system to the map coordinate system z And the preprocessed ship body pose data by using a formula
Determining a roll angle roll, a pitch angle pitch and a translation parameter z in the z direction; wherein, the first and the second end of the pipe are connected with each other,
converting the relation from the laser radar to a map coordinate system;
is a laser radar external parameter matrix;
the preprocessed ship body pose data are obtained;
substituting the roll angle roll, the pitch angle pitch and the translation parameter z in the z direction into the laser radar external reference matrix, converting the three-dimensional external reference calibration into two-dimensional plane calibration, and determining the yaw angle yaw, the translation parameter x in the x direction and the translation parameter y in the y direction.
9. The utility model provides a multiline laser radar external reference calibration system on water which characterized in that includes:
the data acquisition module is used for acquiring the position and pose data of the hull of the unmanned ship and the point cloud data of the buoy;
the data conversion module is used for converting the buoy point cloud data into buoy point cloud data under a map coordinate system by taking a horizontal plane as a reference;
the conversion relation determining module is used for determining the conversion relation from the laser radar coordinate system to the map coordinate system according to the buoy point cloud data;
the external parameter determining module is used for determining the external parameters of the laser radar according to the conversion relation from the laser radar coordinate system to the map coordinate system and the position and attitude data of the ship body; the external parameters of the laser radar comprise a rotation parameter and a translation parameter; the rotation parameters comprise a roll angle, a pitch angle and a yaw angle; the translation parameters comprise translation parameters in the x direction, translation parameters in the y direction and translation parameters in the z direction;
and the calibration module is used for completing the calibration of the laser radar according to the external parameters of the laser radar.
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