ROS学习笔记 06 构建机器人仿真平台
前言
系统环境: Ubuntu 18.04，硬盘安装。
ROS版本: melodic
深蓝学院（古月居）胡春旭ROS理论与实践笔记整理。
1. 优化物理仿真
1.1 xacro基本语法
- 精简模型代码
- 创建宏定义
- 文件包括
- 提供可编程接口
- 常量
- 变量
- 数学计算
- 条件语句
- 常量定义与使用:
<xacro:property name="M_PI" value="3.14159" />
<origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
- 数学计算：
<origin xyz="0 ${(motor_length+wheel_length)/2} 0" rpy = "0 0 0" />
- 宏定义：
<xacro:macro name = "name" params="A B C">
......
</xacro:macro>
- 宏调用:
<name A="A_value" B="B_value" C="C_value" />
- 文件包含：
<xacro:include filename="$(find mbot_description)/urdf/mbot_base_gazebo.xacro" />
1.2 ros_control框架
- ros_control
- ROS为开发者提供的机器人控制中间件
- 包含一系列控制器接口、传动装置接口、硬件接口、控制器工具箱等待
- 可以帮助机器人应用功能包快速落地，提高开发效率。
其中：
- 控制器管理器
提供一种通用的接口来管理不同的控制器。
- 控制器
读取硬件状态，发布控制命令，完成每个joint的控制。
- 硬件资源
为上下两层提供硬件资源的接口。
- 机器人硬件抽象
机器人硬件抽象和硬件资源直接打交道，通过write和read方法完成硬件操作。
- 真实机器人
执行接收到的命令
-
ros_control里主要提供四种控制器：
-
joint_state_controller
-
joint_effort_controller
-
joint_position_controller
-
joint_velocity_controller
-
1.3 模型优化步骤
需要对URDF文件做优化。
- 第一步：为link添加惯性参数和碰撞属性
比如下列代码，base_link的碰撞属性是一个圆柱体，惯性矩阵就是宏cylinder_inertial_matrix，返回的是一个$3\times3$的惯性矩阵。
<xacro:macro name="cylinder_inertial_matrix" params="m r h">
<inertial>
<mass value="${m}" />
<inertia ixx="${m*(3*r*r+h*h)/12}" ixy = "0" ixz = "0"
iyy="${m*(3*r*r+h*h)/12}" iyz = "0"
izz="${m*r*r/2}" />
</inertial>
</xacro:macro>
<link name="base_link">
<visual>
<origin xyz=" 0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="${base_length}" radius="${base_radius}"/>
</geometry>
<material name="yellow" />
</visual>
<collision>
<origin xyz=" 0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="${base_length}" radius="${base_radius}"/>
</geometry>
</collision>
<cylinder_inertial_matrix m="${base_mass}" r="${base_radius}" h="${base_length}" />
</link>
- 第二步：为link添加gazebo标签
这里的<turnGravityOff>是对模型的“影子”base_footprint的重力设置为0。
<gazebo reference="${prefix}_wheel_link">
<material>Gazebo/Gray</material>
</gazebo>
<gazebo reference="${prefix}_caster_link">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="base_footprint">
<turnGravityOff>false</turnGravityOff>
</gazebo>
<gazebo reference="base_link">
<material>Gazebo/Blue</material>
</gazebo>
- 第三步：为joint添加传动装置
- SimpleTransmission: ROS提供的简单的传动装置类型
- 实现了VelocityJointInterface接口
<joint>代表传动关节，<motor>代表电机<mechanicalReduction>代表关节和电机之间的减速比。
<!-- Transmission is important to link the joints and the controller -->
<transmission name="${prefix}_wheel_joint_trans">
<type>transmission_interface/SimpleTransmission</type>
<joint name="${prefix}_wheel_joint" >
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
</joint>
<actuator name="${prefix}_wheel_joint_motor">
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
<mechanicalReduction>1</mechanicalReduction>
</actuator>
</transmission>\
- 第四步：添加gazebo控制器插件
libgazebo_ros_diff_drive.so:ROS提供的差速控制插件。
<!-- controller -->
<gazebo>
<plugin name="differential_drive_controller"
filename="libgazebo_ros_diff_drive.so">
<rosDebugLevel>Debug</rosDebugLevel>
<publishWheelTF>false</publishWheelTF>
<robotNamespace>/</robotNamespace>
<publishTf>1</publishTf>
<publishWheelJointState>false</publishWheelJointState>
<alwaysOn>true</alwaysOn>
<updateRate>100.0</updateRate>
<legacyMode>true</legacyMode>
<leftJoint>left_wheel_joint</leftJoint>
<rightJoint>right_wheel_joint</rightJoint>
<wheelSeparation>${wheel_joint_y*2}</wheelSeparation>
<wheelDiameter>${2*wheel_radius}</wheelDiameter>
<broadcastTF>1</broadcastTF>
<wheelTorque>30</wheelTorque>
<wheelAcceleration>1.8</wheelAcceleration>
<commandTopic>cmd_vel</commandTopic>
<odometryFrame>odom</odometryFrame>
<odometryTopic>odom</odometryTopic>
<robotBaseFrame>base_footprint</robotBaseFrame>
</plugin>
</gazebo>
其中，需要注意的是：
<robotNamespace>：机器人的命名空间，”/”代表不设置命名空间<leftJoint>和<rightJoint>左右轮转动的关节joint。<wheelSeparation>和wheelDiameter：机器人模型的相关尺寸，在计算差速参数时需要用到。<commandTopic>：控制器订阅的速度控制指令，生成全局命名时需要结合<robotNamespace>中设置的命名空间。<odometryFrame>：里程计数据的参考坐标系，ROS中一般都命名为odom。
- 第五步：编写launch文件：
<launch>
<!-- 设置launch文件的参数 -->
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
- 第六步：编写launch文件
<launch>
<!-- 设置launch文件的参数 -->
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
- 第七步: 测试
$ roslaunch mbot_gazebo view_mbot_gazebo_empty_world.launch
2. 创建物理仿真环境
常用的两种方式:
- 第一种方法: 直接添加环境模型(直接insert)
- 第二种方法:使用Gazebo提供的小软件Building Editor
以一个之前保存的仿真环境为例：
<launch>
<!-- 设置launch文件的参数 -->
<arg name="world_name" value="$(find mbot_gazebo)/worlds/playground.world"/>
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="world_name" value="$(arg world_name)" />
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
启动仿真环境：
$ roslaunch mbot_gazebo view_mbot_gazebo_play_ground.launch
编写键盘控制的脚本:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import rospy
from geometry_msgs.msg import Twist
import sys, select, termios, tty
msg = """
Control mbot!
---------------------------
Moving around:
u i o
j k l
m , .
q/z : increase/decrease max speeds by 10%
w/x : increase/decrease only linear speed by 10%
e/c : increase/decrease only angular speed by 10%
space key, k : force stop
anything else : stop smoothly
CTRL-C to quit
"""
moveBindings = {
'i':(1,0),
'o':(1,-1),
'j':(0,1),
'l':(0,-1),
'u':(1,1),
',':(-1,0),
'.':(-1,1),
'm':(-1,-1),
}
speedBindings={
'q':(1.1,1.1),
'z':(.9,.9),
'w':(1.1,1),
'x':(.9,1),
'e':(1,1.1),
'c':(1,.9),
}
def getKey():
tty.setraw(sys.stdin.fileno())
rlist, _, _ = select.select([sys.stdin], [], [], 0.1)
if rlist:
key = sys.stdin.read(1)
else:
key = ''
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, settings)
return key
speed = .2
turn = 1
def vels(speed,turn):
return "currently:\tspeed %s\tturn %s " % (speed,turn)
if __name__=="__main__":
settings = termios.tcgetattr(sys.stdin)
rospy.init_node('mbot_teleop')
pub = rospy.Publisher('/cmd_vel', Twist, queue_size=5)
x = 0
th = 0
status = 0
count = 0
acc = 0.1
target_speed = 0
target_turn = 0
control_speed = 0
control_turn = 0
try:
print msg
print vels(speed,turn)
while(1):
key = getKey()
# 运动控制方向键（1：正方向，-1负方向）
if key in moveBindings.keys():
x = moveBindings[key][0]
th = moveBindings[key][1]
count = 0
# 速度修改键
elif key in speedBindings.keys():
speed = speed * speedBindings[key][0] # 线速度增加0.1倍
turn = turn * speedBindings[key][1] # 角速度增加0.1倍
count = 0
print vels(speed,turn)
if (status == 14):
print msg
status = (status + 1) % 15
# 停止键
elif key == ' ' or key == 'k' :
x = 0
th = 0
control_speed = 0
control_turn = 0
else:
count = count + 1
if count > 4:
x = 0
th = 0
if (key == '\x03'):
break
# 目标速度=速度值*方向值
target_speed = speed * x
target_turn = turn * th
# 速度限位，防止速度增减过快
if target_speed > control_speed:
control_speed = min( target_speed, control_speed + 0.02 )
elif target_speed < control_speed:
control_speed = max( target_speed, control_speed - 0.02 )
else:
control_speed = target_speed
if target_turn > control_turn:
control_turn = min( target_turn, control_turn + 0.1 )
elif target_turn < control_turn:
control_turn = max( target_turn, control_turn - 0.1 )
else:
control_turn = target_turn
# 创建并发布twist消息
twist = Twist()
twist.linear.x = control_speed;
twist.linear.y = 0;
twist.linear.z = 0
twist.angular.x = 0;
twist.angular.y = 0;
twist.angular.z = control_turn
pub.publish(twist)
except:
print e
finally:
twist = Twist()
twist.linear.x = 0; twist.linear.y = 0; twist.linear.z = 0
twist.angular.x = 0; twist.angular.y = 0; twist.angular.z = 0
pub.publish(twist)
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, settings)
编写launch文件：
<launch>
<node name="mbot_teleop" pkg="mbot_teleop" type="mbot_teleop.py" output="screen">
<param name="scale_linear" value="0.1" type="double"/>
<param name="scale_angular" value="0.4" type="double"/>
</node>
</launch>
启动键盘控制：
$ roslaunch mbot_teleop mbot_teleop.launch
3. 传感器仿真
3.1 常规摄像头
写一个宏定义文件camera_gazebo.xacro：
<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="camera">
<xacro:macro name="usb_camera" params="prefix:=camera">
<!-- Create laser reference frame -->
<link name="${prefix}_link">
<inertial>
<mass value="0.1" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz=" 0 0 0 " rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
<material name="black"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
</collision>
</link>
<gazebo reference="${prefix}_link">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="${prefix}_link">
<sensor type="camera" name="camera_node">
<update_rate>30.0</update_rate>
<camera name="head">
<horizontal_fov>1.3962634</horizontal_fov>
<image>
<width>1280</width>
<height>720</height>
<format>R8G8B8</format>
</image>
<clip>
<near>0.02</near>
<far>300</far>
</clip>
<noise>
<type>gaussian</type>
<mean>0.0</mean>
<stddev>0.007</stddev>
</noise>
</camera>
<plugin name="gazebo_camera" filename="libgazebo_ros_camera.so">
<alwaysOn>true</alwaysOn>
<updateRate>0.0</updateRate>
<cameraName>/camera</cameraName>
<imageTopicName>image_raw</imageTopicName>
<cameraInfoTopicName>camera_info</cameraInfoTopicName>
<frameName>camera_link</frameName>
<hackBaseline>0.07</hackBaseline>
<distortionK1>0.0</distortionK1>
<distortionK2>0.0</distortionK2>
<distortionK3>0.0</distortionK3>
<distortionT1>0.0</distortionT1>
<distortionT2>0.0</distortionT2>
</plugin>
</sensor>
</gazebo>
</xacro:macro>
</robot>
需要注意的是：
<sensor>标签：描述传感器- type：传感器类型，camera
- name：摄像头命名，自由设置
<camera>标签：描述摄像头参数- 分辨率，编码格式，图像范围，噪音参数等
<plugin>标签：加载摄像头仿真插件 libgazebo_ros_camera.so- 设置插件的命名空间、发布图像的话题、参考坐标系等
此时，在之前的base_link的宏里把base_link和camera连接起来：
<?xml version="1.0"?>
<robot name="arm" xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:include filename="$(find mbot_description)/urdf/mbot_base_gazebo.xacro" />
<xacro:include filename="$(find mbot_description)/urdf/sensors/camera_gazebo.xacro" />
<xacro:property name="camera_offset_x" value="0.17" />
<xacro:property name="camera_offset_y" value="0" />
<xacro:property name="camera_offset_z" value="0.10" />
<!-- Camera -->
<joint name="camera_joint" type="fixed">
<origin xyz="${camera_offset_x} ${camera_offset_y} ${camera_offset_z}" rpy="0 0 0" />
<parent link="base_link"/>
<child link="camera_link"/>
</joint>
<xacro:usb_camera prefix="camera"/>
<mbot_base_gazebo/>
</robot>
最后，写一个launch文件:
<launch>
<!-- 设置launch文件的参数 -->
<arg name="world_name" value="$(find mbot_gazebo)/worlds/playground.world"/>
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="world_name" value="$(arg world_name)" />
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_with_camera_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
启动仿真环境并使用rqt小工具仿真:
$ roslaunch mbot_gazebo view_mbot_with_camera_gazebo.launch
$ rqt_image_view
左上角改成/camera/image_raw，这样就可以通过rqt小工具仿真虚拟摄像头。
3.2 RGB-D摄像头（kinect）
和camera类似，先写一个宏定义文件:
<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="kinect_camera">
<xacro:macro name="kinect_camera" params="prefix:=camera">
<!-- Create kinect reference frame -->
<!-- Add mesh for kinect -->
<link name="${prefix}_link">
<origin xyz="0 0 0" rpy="0 0 0"/>
<visual>
<origin xyz="0 0 0" rpy="0 0 ${M_PI/2}"/>
<geometry>
<mesh filename="package://mbot_description/meshes/kinect.dae" />
</geometry>
</visual>
<collision>
<geometry>
<box size="0.07 0.3 0.09"/>
</geometry>
</collision>
</link>
<joint name="${prefix}_optical_joint" type="fixed">
<origin xyz="0 0 0" rpy="-1.5708 0 -1.5708"/>
<parent link="${prefix}_link"/>
<child link="${prefix}_frame_optical"/>
</joint>
<link name="${prefix}_frame_optical"/>
<gazebo reference="${prefix}_link">
<sensor type="depth" name="${prefix}">
<always_on>true</always_on>
<update_rate>20.0</update_rate>
<camera>
<horizontal_fov>${60.0*M_PI/180.0}</horizontal_fov>
<image>
<format>R8G8B8</format>
<width>640</width>
<height>480</height>
</image>
<clip>
<near>0.05</near>
<far>8.0</far>
</clip>
</camera>
<plugin name="kinect_${prefix}_controller" filename="libgazebo_ros_openni_kinect.so">
<cameraName>${prefix}</cameraName>
<alwaysOn>true</alwaysOn>
<updateRate>10</updateRate>
<imageTopicName>rgb/image_raw</imageTopicName>
<depthImageTopicName>depth/image_raw</depthImageTopicName>
<pointCloudTopicName>depth/points</pointCloudTopicName>
<cameraInfoTopicName>rgb/camera_info</cameraInfoTopicName>
<depthImageCameraInfoTopicName>depth/camera_info</depthImageCameraInfoTopicName>
<frameName>${prefix}_frame_optical</frameName>
<baseline>0.1</baseline>
<distortion_k1>0.0</distortion_k1>
<distortion_k2>0.0</distortion_k2>
<distortion_k3>0.0</distortion_k3>
<distortion_t1>0.0</distortion_t1>
<distortion_t2>0.0</distortion_t2>
<pointCloudCutoff>0.4</pointCloudCutoff>
</plugin>
</sensor>
</gazebo>
</xacro:macro>
</robot>
在之前的base_link的宏里把base_link和RGB-D连接起来：
<?xml version="1.0"?>
<robot name="arm" xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:include filename="$(find mbot_description)/urdf/mbot_base_gazebo.xacro" />
<xacro:include filename="$(find mbot_description)/urdf/sensors/kinect_gazebo.xacro" />
<xacro:property name="kinect_offset_x" value="0.15" />
<xacro:property name="kinect_offset_y" value="0" />
<xacro:property name="kinect_offset_z" value="0.11" />
<!-- kinect -->
<joint name="kinect_joint" type="fixed">
<origin xyz="${kinect_offset_x} ${kinect_offset_y} ${kinect_offset_z}" rpy="0 0 0" />
<parent link="base_link"/>
<child link="kinect_link"/>
</joint>
<xacro:kinect_camera prefix="kinect"/>
<mbot_base_gazebo/>
</robot>
最后写一个launch文件:
<launch>
<!-- 设置launch文件的参数 -->
<arg name="world_name" value="$(find mbot_gazebo)/worlds/playground.world"/>
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="world_name" value="$(arg world_name)" />
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_with_kinect_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
启动仿真环境：
$ roslaunch mbot_gazebo view_mbot_with_kinect_gazebo.launch
在rviz中显示：
$ rosrun rviz rviz
Add一个pointCloud2，一个robotmodel，topic选择/kinect/depth/points，fixed Frame改成odom，让小车动起来:
$ roslaunch mbot_teleop mbot_teleop.launch
深度图也会随运动改变。
3.3 激光雷达仿真
也和常规camera类似，先写一个宏定义文件:
<launch>
<!-- 设置launch文件的参数 -->
<arg name="world_name" value="$(find mbot_gazebo)/worlds/playground.world"/>
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="world_name" value="$(arg world_name)" />
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_with_laser_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
再连接link：
<?xml version="1.0"?>
<robot name="arm" xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:include filename="$(find mbot_description)/urdf/mbot_base_gazebo.xacro" />
<xacro:include filename="$(find mbot_description)/urdf/sensors/lidar_gazebo.xacro" />
<xacro:property name="lidar_offset_x" value="0" />
<xacro:property name="lidar_offset_y" value="0" />
<xacro:property name="lidar_offset_z" value="0.105" />
<!-- lidar -->
<joint name="lidar_joint" type="fixed">
<origin xyz="${lidar_offset_x} ${lidar_offset_y} ${lidar_offset_z}" rpy="0 0 0" />
<parent link="base_link"/>
<child link="laser_link"/>
</joint>
<xacro:rplidar prefix="laser"/>
<mbot_base_gazebo/>
</robot>
最后写launch文件:
<launch>
<!-- 设置launch文件的参数 -->
<arg name="world_name" value="$(find mbot_gazebo)/worlds/playground.world"/>
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="world_name" value="$(arg world_name)" />
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/mbot_with_laser_gazebo.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen" >
<param name="publish_frequency" type="double" value="50.0" />
</node>
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model mrobot -param robot_description"/>
</launch>
启动仿真环境：
roslaunch mbot_gazebo view_mbot_with_lase_gazebo.launch
在rviz中显示：
$ rosrun rviz rviz
Add一个LaserScan并且topic订阅/scan，add一个robotModel，再键盘控制小车:
$ roslaunch mbot_teleop mbot_teleop.launch
深度图也会随运动改变。