ROS 2中如何将URDF加载到RViz
在本教程中,将学习在ROS 2中如何将URDF加载到RViz中。统一机器人描述格式URDF是ROS中机器人建模的标准格式。
目录
一、前提条件
二、创建一个ROS 2软件包
三、创建其它目录
四、创建URDF文件
五、添加依赖项
六、创建启动文件
七、添加RViz配置文件
八、编译构建软件包
九、在RViz中启动机器人
一、前提条件
·已在Ubuntu Linux 20.04操作系统中安装好ROS 2 Foxy Fitzroy
·如果使用的是ROS 2的其它发行版,则需要在本教程中提到“foxy”的任何地方将“foxy”替换为您的发行版名称(例如“galactic”)。
·强烈建议您获取最新版本的 ROS 2。如果您使用的是较新版本的 ROS 2,仍然可以按照本教程中的所有步骤进行操作。一切都能正常工作的。
·您已经创建好了一个ROS 2工作空间。在本教程中该工作空间的名称为“dev_ws”,代表“开发工作空间”。
·您已经完成了上一教程的学习,已经了解了URDF是什么,且已经安装好了ROS 2的重要相关软件包。
可以在Google Drive此处找到本教程的完整代码。
二、创建一个ROS 2软件包
现在让我们在工作空间中创建一个ROS 2软件包。
在一个新的终端窗口中,进入到您工作空间存放源代码的src目录:
cd ~/dev_ws/src
现在使用以下命令来创建一个名为two_wheeled_robot的软件包:
ros2 pkg create --build-type ament_cmake two_wheeled_robot
三、创建其它目录
进入到该软件包目录中:
cd ~/dev_ws/src/ two_wheeled_robot
使用以下命令来创建一些其它目录:
mkdir config launch maps meshes models params rviz worlds
键入以下命令以确认这些目录创建成功:
dir
四、创建URDF文件
在本节中将会逐步构建该移动机器人。该机器人将会用一种表示机器人模型的 XML 文件即统一机器人描述格式(URDF)定义。
打开一个新的终端窗口,并键入以下命令:
cd ~/dev_ws/src/ two_wheeled_robot
cd urdf
创建一个名为two_wheeled_robot.urdf的新文件:
gedit two_wheeled_robot
在这个文件中,我们会定义机器人的外观(即视觉属性)、机器人在碰撞到物体时的行为(即碰撞属性)及其质量(即惯性属性)。
在该URDF文件中复制粘贴下面这段代码:
<?xml version="1.0" ?>
<robot name="two_wheeled_robot" xmlns:xacro="http://ros.org/wiki/xacro">
<!-- ****************** ROBOT CONSTANTS ******************************* -->
<!-- Define the size of the robot's main chassis in meters -->
<xacro:property name="base_width" value="0.39"/>
<xacro:property name="base_length" value="0.70"/>
<xacro:property name="base_height" value="0.20"/>
<!-- Define the shape of the robot's two back wheels in meters -->
<xacro:property name="wheel_radius" value="0.14"/>
<xacro:property name="wheel_width" value="0.06"/>
<!-- x-axis points forward, y-axis points to left, z-axis points upwards -->
<!-- Define the gap between the wheel and chassis along y-axis in meters -->
<xacro:property name="wheel_ygap" value="0.035"/>
<!-- Position the wheels along the z-axis -->
<xacro:property name="wheel_zoff" value="0.05"/>
<!-- Position the wheels along the x-axis -->
<xacro:property name="wheel_xoff" value="0.221"/>
<!-- Position the caster wheel along the x-axis -->
<xacro:property name="caster_xoff" value="0.217"/>
<!-- Define intertial property macros -->
<xacro:macro name="box_inertia" params="m w h d">
<inertial>
<origin xyz="0 0 0" rpy="${pi/2} 0 ${pi/2}"/>
<mass value="${m}"/>
<inertia ixx="${(m/12) * (h*h + d*d)}" ixy="0.0" ixz="0.0" iyy="${(m/12) * (w*w + d*d)}" iyz="0.0" izz="${(m/12) * (w*w + h*h)}"/>
</inertial>
</xacro:macro>
<xacro:macro name="cylinder_inertia" params="m r h">
<inertial>
<origin xyz="0 0 0" rpy="${pi/2} 0 0" />
<mass value="${m}"/>
<inertia ixx="${(m/12) * (3*r*r + h*h)}" ixy = "0" ixz = "0" iyy="${(m/12) * (3*r*r + h*h)}" iyz = "0" izz="${(m/2) * (r*r)}"/>
</inertial>
</xacro:macro>
<xacro:macro name="sphere_inertia" params="m r">
<inertial>
<mass value="${m}"/>
<inertia ixx="${(2/5) * m * (r*r)}" ixy="0.0" ixz="0.0" iyy="${(2/5) * m * (r*r)}" iyz="0.0" izz="${(2/5) * m * (r*r)}"/>
</inertial>
</xacro:macro>
<!-- ****************** ROBOT BASE FOOTPRINT *************************** -->
<!-- Define the center of the main robot chassis projected on the ground -->
<link name="base_footprint"/>
<!-- The base footprint of the robot is located underneath the chassis -->
<joint name="base_joint" type="fixed">
<parent link="base_footprint"/>
<child link="base_link" />
<origin xyz="0.0 0.0 ${(wheel_radius+wheel_zoff)}" rpy="0 0 0"/>
</joint>
<!-- ********************** ROBOT BASE ********************************* -->
<link name="base_link">
<visual>
<origin xyz="0 0 -0.05" rpy="1.5707963267949 0 3.141592654"/>
<geometry>
<mesh filename="package://two_wheeled_robot/meshes/robot_base.stl" />
</geometry>
<material name="Red">
<color rgba="${255/255} ${0/255} ${0/255} 1.0"/>
</material>
</visual>
<collision>
<geometry>
<box size="${base_length} ${base_width} ${base_height}"/>
</geometry>
</collision>
<xacro:box_inertia m="40.0" w="${base_width}" d="${base_length}" h="${base_height}"/>
</link>
<gazebo reference="base_link">
<material>Gazebo/Red</material>
</gazebo>
<!-- *********************** DRIVE WHEELS ****************************** -->
<xacro:macro name="wheel" params="prefix x_reflect y_reflect">
<link name="${prefix}_link">
<visual>
<origin xyz="0 0 0" rpy="1.5707963267949 0 0"/>
<geometry>
<cylinder radius="${wheel_radius}" length="${wheel_width}"/>
</geometry>
<material name="White">
<color rgba="${255/255} ${255/255} ${255/255} 1.0"/>
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="${pi/2} 0 0"/>
<geometry>
<cylinder radius="${wheel_radius}" length="${wheel_width}"/>
</geometry>
</collision>
<xacro:cylinder_inertia m="110.5" r="${wheel_radius}" h="${wheel_width}"/>
</link>
<!-- Connect the wheels to the base_link at the appropriate location, and
define a continuous joint to allow the wheels to freely rotate about
an axis -->
<joint name="${prefix}_joint" type="revolute">
<parent link="base_link"/>
<child link="${prefix}_link"/>
<origin xyz="${x_reflect*wheel_xoff} ${y_reflect*(base_width/2+wheel_ygap)} ${-wheel_zoff}" rpy="0 0 0"/>
<limit upper="3.1415" lower="-3.1415" effort="30" velocity="5.0"/>
<axis xyz="0 1 0"/>
</joint>
</xacro:macro>
<!-- Instantiate two wheels using the macro we just made through the
xacro:wheel tags. We also define the parameters to have one wheel
on both sides at the back of our robot (i.e. x_reflect=-1). -->
<xacro:wheel prefix="drivewhl_l" x_reflect="-1" y_reflect="1" />
<xacro:wheel prefix="drivewhl_r" x_reflect="-1" y_reflect="-1" />
<!-- *********************** CASTER WHEEL ****************************** -->
<!-- We add a caster wheel. It will be modeled as sphere.
We define the wheel’s geometry, material and the joint to connect it to
base_link at the appropriate location. -->
<link name="front_caster">
<visual>
<geometry>
<sphere radius="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
</geometry>
<material name="White">
<color rgba="${255/255} ${255/255} ${255/255} 1.0"/>
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
</geometry>
</collision>
<xacro:sphere_inertia m="10.05" r="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
</link>
<gazebo reference="front_caster">
<mu1>0.01</mu1>
<mu2>0.01</mu2>
<material>Gazebo/White</material>
</gazebo>
<joint name="caster_joint" type="fixed">
<parent link="base_link"/>
<child link="front_caster"/>
<origin xyz="${caster_xoff} 0.0 ${-(base_height/2)}" rpy="0 0 0"/>
</joint>
<!-- *********************** IMU SETUP ********************************* -->
<!-- Each sensor must be attached to a link. -->
<joint name="imu_joint" type="fixed">
<parent link="base_link"/>
<child link="imu_link"/>
<origin xyz="-0.10 0 0.05" rpy="0 0 0"/>
</joint>
<link name="imu_link"/>
<!-- *********************** LIDAR SETUP ********************************** -->
<joint name="lidar_joint" type="fixed">
<parent link="base_link"/>
<child link="lidar_link"/>
<origin xyz="0.215 0 0.13" rpy="0 0 0"/>
</joint>
<link name="lidar_link">
<collision>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<cylinder radius="0.0508" length="0.18"/>
</geometry>
</collision>
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<cylinder radius="0.0508" length="0.18"/>
</geometry>
<material name="Black">
<color rgba="${0/255} ${0/255} ${0/255} 1.0"/>
</material>
</visual>
<inertial>
<mass value="0.114" />
<origin xyz="0 0 0" rpy="0 0 0"/>
<inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001" />
</inertial>
</link>
</robot>
保存并关闭该文件。
五、添加依赖项
现在来添加一些我们项目要依赖的软件包。使用以下命令进入到 package.xml 文件中:
cd ~/dev_ws/src/two_wheeled_robot
gedit package.xml
在<buildtool_depend>标签之后添加以下几行:
<exec_depend>joint_state_publisher</exec_depend>
<exec_depend>robot_state_publisher</exec_depend>
<exec_depend>rviz</exec_depend>
<exec_depend>xacro</exec_depend>
保存并关闭该文件。
我们会用到Joint State Publisher和Robot State Publisher。此外还会用到RViz来可视化机器人模型。
六、创建启动文件
现在来创建启动文件。打开一个新的终端窗口并键入以下命令:
cd ~/dev_ws/src/ two_wheeled_robot
cd launch
gedit two_wheeled_robot.launch.py
将下面这段代码复制并粘贴到该文件中:
# Author: Addison Sears-Collins
# Date: September 14, 2021
# Description: Launch a two-wheeled robot URDF file using Rviz.
# https://automaticaddison.com
import os
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.conditions import IfCondition, UnlessCondition
from launch.substitutions import Command, LaunchConfiguration
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare
def generate_launch_description():
# Set the path to this package.
pkg_share = FindPackageShare(package='two_wheeled_robot').find('two_wheeled_robot')
# Set the path to the RViz configuration settings
default_rviz_config_path = os.path.join(pkg_share, 'rviz/rviz_basic_settings.rviz')
# Set the path to the URDF file
default_urdf_model_path = os.path.join(pkg_share, 'urdf/two_wheeled_robot.urdf')
########### YOU DO NOT NEED TO CHANGE ANYTHING BELOW THIS LINE ##############
# Launch configuration variables specific to simulation
gui = LaunchConfiguration('gui')
urdf_model = LaunchConfiguration('urdf_model')
rviz_config_file = LaunchConfiguration('rviz_config_file')
use_robot_state_pub = LaunchConfiguration('use_robot_state_pub')
use_rviz = LaunchConfiguration('use_rviz')
use_sim_time = LaunchConfiguration('use_sim_time')
# Declare the launch arguments
declare_urdf_model_path_cmd = DeclareLaunchArgument(
name='urdf_model',
default_value=default_urdf_model_path,
description='Absolute path to robot urdf file')
declare_rviz_config_file_cmd = DeclareLaunchArgument(
name='rviz_config_file',
default_value=default_rviz_config_path,
description='Full path to the RVIZ config file to use')
declare_use_joint_state_publisher_cmd = DeclareLaunchArgument(
name='gui',
default_value='True',
description='Flag to enable joint_state_publisher_gui')
declare_use_robot_state_pub_cmd = DeclareLaunchArgument(
name='use_robot_state_pub',
default_value='True',
description='Whether to start the robot state publisher')
declare_use_rviz_cmd = DeclareLaunchArgument(
name='use_rviz',
default_value='True',
description='Whether to start RVIZ')
declare_use_sim_time_cmd = DeclareLaunchArgument(
name='use_sim_time',
default_value='True',
description='Use simulation (Gazebo) clock if true')
# Specify the actions
# Publish the joint state values for the non-fixed joints in the URDF file.
start_joint_state_publisher_cmd = Node(
condition=UnlessCondition(gui),
package='joint_state_publisher',
executable='joint_state_publisher',
name='joint_state_publisher')
# A GUI to manipulate the joint state values
start_joint_state_publisher_gui_node = Node(
condition=IfCondition(gui),
package='joint_state_publisher_gui',
executable='joint_state_publisher_gui',
name='joint_state_publisher_gui')
# Subscribe to the joint states of the robot, and publish the 3D pose of each link.
start_robot_state_publisher_cmd = Node(
condition=IfCondition(use_robot_state_pub),
package='robot_state_publisher',
executable='robot_state_publisher',
parameters=[{'use_sim_time': use_sim_time,
'robot_description': Command(['xacro ', urdf_model])}],
arguments=[default_urdf_model_path])
# Launch RViz
start_rviz_cmd = Node(
condition=IfCondition(use_rviz),
package='rviz2',
executable='rviz2',
name='rviz2',
output='screen',
arguments=['-d', rviz_config_file])
# Create the launch description and populate
ld = LaunchDescription()
# Declare the launch options
ld.add_action(declare_urdf_model_path_cmd)
ld.add_action(declare_rviz_config_file_cmd)
ld.add_action(declare_use_joint_state_publisher_cmd)
ld.add_action(declare_use_robot_state_pub_cmd)
ld.add_action(declare_use_rviz_cmd)
ld.add_action(declare_use_sim_time_cmd)
# Add any actions
ld.add_action(start_joint_state_publisher_cmd)
ld.add_action(start_joint_state_publisher_gui_node)
ld.add_action(start_robot_state_publisher_cmd)
ld.add_action(start_rviz_cmd)
return ld
保存并关闭该文件。
可以在此处查阅更多有关启动(launch)文件的信息。
七、添加RViz配置文件
现在来添加一个配置文件,该配置文件将会使用适当的设置初始化RViz,以便可以在RViz启动后立即浏览该机器人。
打开一个新的终端窗口,并键入以下命令:
cd ~/dev_ws/src/ two_wheeled_robot
cd rviz
gedit rviz_basic_settings.rviz
将下面这段代码复制粘贴到该文件中,然后保存并关闭该文件:
Panels:
- Class: rviz_common/Displays
Help Height: 78
Name: Displays
Property Tree Widget:
Expanded:
- /Global Options1
- /Status1
- /RobotModel1
- /TF1
- /TF1/Frames1
Splitter Ratio: 0.5
Tree Height: 617
- Class: rviz_common/Selection
Name: Selection
- Class: rviz_common/Tool Properties
Expanded:
- /2D Goal Pose1
- /Publish Point1
Name: Tool Properties
Splitter Ratio: 0.5886790156364441
- Class: rviz_common/Views
Expanded:
- /Current View1
Name: Views
Splitter Ratio: 0.5
Visualization Manager:
Class: ""
Displays:
- Alpha: 0.5
Cell Size: 1
Class: rviz_default_plugins/Grid
Color: 160; 160; 164
Enabled: true
Line Style:
Line Width: 0.029999999329447746
Value: Lines
Name: Grid
Normal Cell Count: 0
Offset:
X: 0
Y: 0
Z: 0
Plane: XY
Plane Cell Count: 10
Reference Frame: <Fixed Frame>
Value: true
- Alpha: 1
Class: rviz_default_plugins/RobotModel
Collision Enabled: false
Description File: ""
Description Source: Topic
Description Topic:
Depth: 5
Durability Policy: Volatile
History Policy: Keep Last
Reliability Policy: Reliable
Value: /robot_description
Enabled: true
Links:
All Links Enabled: true
Expand Joint Details: false
Expand Link Details: false
Expand Tree: false
Link Tree Style: Links in Alphabetic Order
base_footprint:
Alpha: 1
Show Axes: false
Show Trail: false
base_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
drivewhl_l_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
drivewhl_r_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
front_caster:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
gps_link:
Alpha: 1
Show Axes: false
Show Trail: false
imu_link:
Alpha: 1
Show Axes: false
Show Trail: false
lidar_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
Name: RobotModel
TF Prefix: ""
Update Interval: 0
Value: true
Visual Enabled: true
- Class: rviz_default_plugins/TF
Enabled: true
Frame Timeout: 15
Frames:
All Enabled: false
base_footprint:
Value: false
base_link:
Value: false
drivewhl_l_link:
Value: true
drivewhl_r_link:
Value: true
front_caster:
Value: false
gps_link:
Value: false
imu_link:
Value: false
lidar_link:
Value: false
Marker Scale: 1
Name: TF
Show Arrows: false
Show Axes: true
Show Names: true
Tree:
base_footprint:
base_link:
drivewhl_l_link:
{}
drivewhl_r_link:
{}
front_caster:
{}
gps_link:
{}
imu_link:
{}
lidar_link:
{}
Update Interval: 0
Value: true
Enabled: true
Global Options:
Background Color: 48; 48; 48
Fixed Frame: base_link
Frame Rate: 30
Name: root
Tools:
- Class: rviz_default_plugins/Interact
Hide Inactive Objects: true
- Class: rviz_default_plugins/MoveCamera
- Class: rviz_default_plugins/Select
- Class: rviz_default_plugins/FocusCamera
- Class: rviz_default_plugins/Measure
Line color: 128; 128; 0
- Class: rviz_default_plugins/SetInitialPose
Topic:
Depth: 5
Durability Policy: Volatile
History Policy: Keep Last
Reliability Policy: Reliable
Value: /initialpose
- Class: rviz_default_plugins/SetGoal
Topic:
Depth: 5
Durability Policy: Volatile
History Policy: Keep Last
Reliability Policy: Reliable
Value: /goal_pose
- Class: rviz_default_plugins/PublishPoint
Single click: true
Topic:
Depth: 5
Durability Policy: Volatile
History Policy: Keep Last
Reliability Policy: Reliable
Value: /clicked_point
Transformation:
Current:
Class: rviz_default_plugins/TF
Value: true
Views:
Current:
Class: rviz_default_plugins/Orbit
Distance: 4.434264183044434
Enable Stereo Rendering:
Stereo Eye Separation: 0.05999999865889549
Stereo Focal Distance: 1
Swap Stereo Eyes: false
Value: false
Focal Point:
X: 0.31193429231643677
Y: 0.11948385089635849
Z: -0.4807402193546295
Focal Shape Fixed Size: true
Focal Shape Size: 0.05000000074505806
Invert Z Axis: false
Name: Current View
Near Clip Distance: 0.009999999776482582
Pitch: 0.490397572517395
Target Frame: <Fixed Frame>
Value: Orbit (rviz)
Yaw: 1.0503965616226196
Saved: ~
Window Geometry:
Displays:
collapsed: false
Height: 846
Hide Left Dock: false
Hide Right Dock: false
QMainWindow State: 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
Selection:
collapsed: false
Tool Properties:
collapsed: false
Views:
collapsed: false
Width: 1200
X: 246
Y: 77
八、编译构建软件包
现在就可以编译构建该软件包了。打开一个新的终端窗口并输入以下命令:
cd ~/dev_ws/src/two_wheeled_robot
gedit CMakeLists.txt
将下面这个代码段添加到CMakeLists.txt文件中的if(BUILD_TESTING)代码行前面:
install(
DIRECTORY config launch maps meshes models params rviz src urdf worlds
DESTINATION share/${PROJECT_NAME}
)
保存并关闭该文件。
编译该软件包:
cd ~/dev_ws/
colcon build
如果在您的工作空间中还有其它软件包,而且您只想构建two_wheeled_robot软件包,则需要键入以下命令:
colcon build --packages-select two_wheeled_robot
九、在RViz中启动机器人
打开一个新的终端窗口,并输入以下命令:
cd ~/dev_ws/
ros2 launch two_wheeled_robot two_wheeled_robot.launch.py
在RViz中启动该机器人后的输出结果应该如下图所示:
本教程就是这样。
完成所有任务后,请在所有终端窗口中按 CTRL+C 组合键关闭所有程序。
*英语原文地址:https://automaticaddison.com/ho
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