urdf文件很直白，每個零件的</link>??</joint>都要編寫一遍，每個零件數(shù)據(jù)都要自己算出來結(jié)果，很麻煩，但是用起來很簡單。xacro寫的模型文件可以把好多常量提前定義出來，不同大小的機(jī)器人只要只要改一下常量，機(jī)器人模型就可以重新生成，代碼可以復(fù)用，編寫起來簡單多了，但是編寫launch啟動文件麻煩一些。

urdf編寫的小車模型文件：

<!-- base.urdf -->
<?xml version="1.0" ?>
<robot name="jtbot">
  <!-- 機(jī)器人底盤 -->
  <link name="base_link">
    <visual>
      <geometry>
        <box size="0.46 0.46 0.11"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <geometry>
        <box size="0.46 0.46 0.11"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="1.5707963267948966 0 1.5707963267948966" xyz="0 0 0"/>
      <mass value="15"/>
      <inertia ixx="0.279625" ixy="0.0" ixz="0.0" iyy="0.529" iyz="0.0" izz="0.279625"/>
    </inertial>
  </link>
  <!-- 機(jī)器人 Footprint -->
  <link name="base_footprint"/>
  <!-- 底盤關(guān)節(jié) -->
  <joint name="base_joint" type="fixed">
    <parent link="base_link"/>
    <child link="base_footprint"/>
    <origin rpy="0 0 0" xyz="0.0 0.0 -0.1325"/>
  </joint>
  <link name="left_wheel_link">
    <visual>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.06" radius="0.0775"/>
      </geometry>
      <material name="Gray">
        <color rgba="0.5 0.5 0.5 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.06" radius="0.0775"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <mass value="0.8"/>
      <inertia ixx="0.0014412499999999998" ixy="0" ixz="0" iyy="0.0014412499999999998" iyz="0" izz="0.0024025"/>
    </inertial>
  </link>
  <!-- 輪子關(guān)節(jié) -->
  <joint name="left_wheel_joint" type="continuous">
    <parent link="base_link"/>
    <child link="left_wheel_link"/>
    <origin rpy="0 0 0" xyz="0.15 0.27 -0.055"/>
    <axis xyz="0 1 0"/>
  </joint>
  <link name="right_wheel_link">
    <visual>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.06" radius="0.0775"/>
      </geometry>
      <material name="Gray">
        <color rgba="0.5 0.5 0.5 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.06" radius="0.0775"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
      <mass value="0.8"/>
      <inertia ixx="0.0014412499999999998" ixy="0" ixz="0" iyy="0.0014412499999999998" iyz="0" izz="0.0024025"/>
    </inertial>
  </link>
  <!-- 輪子關(guān)節(jié) -->
  <joint name="right_wheel_joint" type="continuous">
    <parent link="base_link"/>
    <child link="right_wheel_link"/>
    <origin rpy="0 0 0" xyz="0.15 -0.27 -0.055"/>
    <axis xyz="0 1 0"/>
  </joint>
  <!-- 支撐輪 -->
  <link name="caster_link">
    <visual>
      <geometry>
        <sphere radius="0.03875"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <sphere radius="0.03875"/>
      </geometry>
    </collision>
    <inertial>
      <mass value="0.5"/>
      <inertia ixx="0.0003003125" ixy="0.0" ixz="0.0" iyy="0.0003003125" iyz="0.0" izz="0.0003003125"/>
    </inertial>
  </link>
  <!-- 支撐輪gazebo顏色 -->
  <gazebo reference="caster_link">
    <material>Gazebo/Black</material>
  </gazebo>
  <!-- 支撐輪gazebo摩擦力 -->
  <gazebo reference="caster_link">
    <mu1 value="0.0"/>
    <mu2 value="0.0"/>
    <kp value="1000000.0"/>
    <kd value="10.0"/>
  </gazebo>
  <!-- 支撐輪關(guān)節(jié) -->
  <joint name="caster_joint" type="fixed">
    <parent link="base_link"/>
    <child link="caster_link"/>
    <origin rpy="0 0 0" xyz="-0.205 0.0 -0.09375"/>
  </joint>
  <!-- imu -->
  <link name="imu_link">
    <visual>
      <geometry>
        <box size="0.06 0.03 0.03"/>
      </geometry>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <geometry>
        <box size="0.06 0.03 0.03"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="1.5707963267948966 0 1.5707963267948966" xyz="0 0 0"/>
      <mass value="0.1"/>
      <inertia ixx="0.0001666666666666667" ixy="0.0" ixz="0.0" iyy="0.0001666666666666667" iyz="0.0" izz="0.0001666666666666667"/>
    </inertial>
  </link>
  <!-- imu關(guān)節(jié) -->
  <joint name="imu_joint" type="fixed">
    <parent link="base_link"/>
    <child link="imu_link"/>
    <origin xyz="-0.05 0 -0.055"/>
  </joint>
  <!-- imu仿真插件 -->
  <gazebo reference="imu_link">
    <sensor name="imu_sensor" type="imu">
      <plugin filename="libgazebo_ros_imu_sensor.so" name="imu_plugin">
        <ros>
          <!-- 命名空間 -->
          <!-- <namespace>/demo</namespace> -->
          <remapping>~/out:=imu</remapping>
        </ros>
        <!-- 初始方位_參考 -->
        <initial_orientation_as_reference>false</initial_orientation_as_reference>
      </plugin>
      <always_on>true</always_on>
      <!-- 更新頻率 -->
      <update_rate>100</update_rate>
      <visualize>true</visualize>
      <imu>
        <!-- 角速度 -->
        <angular_velocity>
          <x>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </x>
          <y>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </y>
          <z>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </z>
        </angular_velocity>
        <!-- 線性加速度 -->
        <linear_acceleration>
          <x>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </x>
          <y>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </y>
          <z>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </z>
        </linear_acceleration>
      </imu>
    </sensor>
  </gazebo>
  <!-- 差速驅(qū)動仿真插件 -->
  <gazebo>
    <plugin filename="libgazebo_ros_diff_drive.so" name="diff_drive">
      <ros>
        <!-- 命名空間 -->
        <!-- <namespace>/demo</namespace> -->
      </ros>
      <!-- 左右輪子 -->
      <left_joint>left_wheel_joint</left_joint>
      <right_joint>right_wheel_joint</right_joint>
      <!-- 輪距 輪子直徑 -->
      <wheel_separation>0.52</wheel_separation>
      <!-- <wheel_separation>0.52</wheel_separation> -->
      <wheel_diameter>0.155</wheel_diameter>
      <!-- <wheel_diameter>0.155</wheel_diameter> -->
      <!-- 最大扭矩 最大加速度 -->
      <max_wheel_torque>20</max_wheel_torque>
      <max_wheel_acceleration>1.0</max_wheel_acceleration>
      <!-- 輸出 -->
      <!-- 是否發(fā)布里程計 -->
      <publish_odom>true</publish_odom>
      <!-- 是否發(fā)布里程計的tf開關(guān) -->
      <publish_odom_tf>true</publish_odom_tf>
      <!-- 是否發(fā)布輪子的tf數(shù)據(jù)開關(guān) -->
      <publish_wheel_tf>true</publish_wheel_tf>
      <!-- 里程計的framed ID，最終體現(xiàn)在話題和TF上 -->
      <odometry_frame>odom</odometry_frame>
      <!-- 機(jī)器人的基礎(chǔ)frame的ID -->
      <robot_base_frame>base_link</robot_base_frame>
    </plugin>
  </gazebo>
  <!-- 雷達(dá) -->
  <link name="laser">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.04" radius="0.04"/>
      </geometry>
    </visual>
    <!-- 慣性屬性 -->
    <inertial>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <mass value="0.125"/>
      <inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001"/>
    </inertial>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.04" radius="0.04"/>
      </geometry>
    </collision>
  </link>
  <!-- 雷達(dá)關(guān)節(jié) -->
  <joint name="laser_joint" type="fixed">
    <parent link="base_link"/>
    <child link="laser"/>
    <origin rpy="0 0 0" xyz="0.16 0 0.078"/>
  </joint>
  <gazebo reference="laser">
    <sensor name="laser" type="ray">
      <always_on>true</always_on>
      <visualize>false</visualize>
      <update_rate>5</update_rate>
      <ray>
        <scan>
          <horizontal>
            <samples>360</samples>
            <resolution>1.000000</resolution>
            <min_angle>0.000000</min_angle>
            <max_angle>6.280000</max_angle>
          </horizontal>
        </scan>
        <range>
          <min>0.120000</min>
          <max>3.5</max>
          <resolution>0.015000</resolution>
        </range>
        <noise>
          <type>gaussian</type>
          <mean>0.0</mean>
          <stddev>0.01</stddev>
        </noise>
      </ray>
      <plugin filename="libgazebo_ros_ray_sensor.so" name="scan">
        <ros>
          <remapping>~/out:=scan</remapping>
        </ros>
        <output_type>sensor_msgs/LaserScan</output_type>
        <frame_name>laser</frame_name>
      </plugin>
    </sensor>
  </gazebo>
  <!-- 相機(jī) -->
  <link name="camera_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <box size="0.015 0.130 0.022"/>
      </geometry>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <box size="0.015 0.130 0.022"/>
      </geometry>
    </collision>
    <!-- 慣性屬性 -->
    <inertial>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <mass value="0.035"/>
      <inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001"/>
    </inertial>
  </link>
  <!-- 相機(jī)關(guān)節(jié) -->
  <joint name="camera_joint" type="fixed">
    <parent link="base_link"/>
    <child link="camera_link"/>
    <origin rpy="0 0 0" xyz="0.16 0 0.11"/>
  </joint>
  <!-- 深度相機(jī) -->
  <link name="camera_depth_frame"/>
  <joint name="camera_depth_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <parent link="camera_link"/>
    <child link="camera_depth_frame"/>
  </joint>
  <!-- 相機(jī)仿真 -->
  <gazebo reference="camera_depth_link">
    <sensor name="depth_camera" type="depth">
      <visualize>true</visualize>
      <update_rate>30.0</update_rate>
      <camera name="camera">
        <horizontal_fov>1.047198</horizontal_fov>
        <image>
          <width>640</width>
          <height>480</height>
          <format>R8G8B8</format>
        </image>
        <clip>
          <near>0.05</near>
          <far>3</far>
        </clip>
      </camera>
      <plugin filename="libgazebo_ros_camera.so" name="depth_camera_controller">
        <baseline>0.2</baseline>
        <alwaysOn>true</alwaysOn>
        <updateRate>0.0</updateRate>
        <frame_name>camera_depth_frame</frame_name>
        <pointCloudCutoff>0.5</pointCloudCutoff>
        <pointCloudCutoffMax>3.0</pointCloudCutoffMax>
        <distortionK1>0</distortionK1>
        <distortionK2>0</distortionK2>
        <distortionK3>0</distortionK3>
        <distortionT1>0</distortionT1>
        <distortionT2>0</distortionT2>
        <CxPrime>0</CxPrime>
        <Cx>0</Cx>
        <Cy>0</Cy>
        <focalLength>0</focalLength>
        <hackBaseline>0</hackBaseline>
      </plugin>
    </sensor>
  </gazebo>
</robot>

xacro編寫的小車模型文件：

<!-- base.urdf.xacro -->
<?xml version="1.0"?>
<robot name="jtbot"
  xmlns:xacro="http://ros.org/wiki/xacro">

  <!-- 定義機(jī)器人常量 -->
  <!-- 底盤 長 寬 高 -->
  <xacro:property name="base_width" value="0.46"/>
  <xacro:property name="base_length" value="0.46"/>
  <xacro:property name="base_height" value="0.11"/>
  <!-- 輪子半徑 -->
  <xacro:property name="wheel_radius" value="0.0775"/>
  <!-- 輪子寬度 -->
  <xacro:property name="wheel_width" value="0.06"/>
  <!-- 輪子和底盤的間距 -->
  <xacro:property name="wheel_ygap" value="0.01"/>
  <!-- 輪子z軸偏移量 -->
  <xacro:property name="wheel_zoff" value="0.055"/>
  <!-- 輪子x軸偏移量 -->
  <xacro:property name="wheel_xoff" value="0.15"/>
  <!-- 支撐輪x軸偏移量 -->
  <xacro:property name="caster_xoff" value="0.205"/>

  <!-- 定義長方形慣性屬性宏  -->
  <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="${(m/12) * (w*w + h*h)}"/>
    </inertial>
  </xacro:macro>
  <!-- 定義圓柱慣性屬性宏  -->
  <xacro:macro name="cylinder_inertia" params="m r h">
    <inertial>
      <origin xyz="0 0 0" rpy="${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>
  <!-- 定義球體慣性屬性宏  -->
  <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>

  <!-- 機(jī)器人底盤 -->
  <link name="base_link">
    <visual>
      <geometry>
        <box size="${base_length} ${base_width} ${base_height}"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <geometry>
        <box size="${base_length} ${base_width} ${base_height}"/>
      </geometry>
    </collision>
    <!-- 慣性特性 -->
    <xacro:box_inertia m="15" w="${base_width}" d="${base_length}" h="${base_height}"/>
  </link>

  <!-- 機(jī)器人 Footprint -->
  <link name="base_footprint"/>
  <!-- 底盤關(guān)節(jié) -->
  <joint name="base_joint" type="fixed">
    <parent link="base_link"/>
    <child link="base_footprint"/>
    <origin xyz="0.0 0.0 ${-(wheel_radius+wheel_zoff)}" rpy="0 0 0"/>
  </joint>

  <!-- 創(chuàng)建輪子宏函數(shù) -->
  <xacro:macro name="wheel" params="prefix x_reflect y_reflect">
    <link name="${prefix}_link">
      <visual>
        <origin xyz="0 0 0" rpy="${pi/2} 0 0"/>
        <geometry>
          <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
        </geometry>
        <material name="Gray">
          <color rgba="0.5 0.5 0.5 1.0"/>
        </material>
      </visual>
      <!-- 碰撞區(qū)域 -->
      <collision>
        <origin xyz="0 0 0" rpy="${pi/2} 0 0"/>
        <geometry>
          <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
        </geometry>
      </collision>
      <!-- 慣性屬性 -->
      <xacro:cylinder_inertia m="0.8" r="${wheel_radius}" h="${wheel_width}"/>
    </link>
    <!-- 輪子關(guān)節(jié) -->
    <joint name="${prefix}_joint" type="continuous">
      <parent link="base_link"/>
      <child link="${prefix}_link"/>
      <origin xyz="${x_reflect*wheel_xoff} ${y_reflect*(base_width/2+wheel_width/2+wheel_ygap)} ${-wheel_zoff}" rpy="0 0 0"/>
      <axis xyz="0 1 0"/>
    </joint>
  </xacro:macro>
  <!-- 根據(jù)上面的宏函數(shù)實(shí)例化左右輪 -->
  <xacro:wheel prefix="left_wheel" x_reflect="1" y_reflect="1" />
  <xacro:wheel prefix="right_wheel" x_reflect="1" y_reflect="-1" />

  <!-- 支撐輪 -->
  <link name="caster_link">
    <visual>
      <geometry>
        <sphere radius="${(wheel_radius/2)}"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <sphere radius="${(wheel_radius/2)}"/>
      </geometry>
    </collision>
    <!-- 慣性屬性 -->
    <xacro:sphere_inertia m="0.5" r="${(wheel_radius/2)}"/>
  </link>
  <!-- 支撐輪gazebo顏色 -->
  <gazebo reference="caster_link">
    <material>Gazebo/Black</material>
  </gazebo>
  <!-- 支撐輪gazebo摩擦力 -->
  <gazebo reference="caster_link">
    <mu1 value="0.0"/>
    <mu2 value="0.0"/>
    <kp value="1000000.0" />
    <kd value="10.0" />
  </gazebo>
  <!-- 支撐輪關(guān)節(jié) -->
  <joint name="caster_joint" type="fixed">
    <parent link="base_link"/>
    <child link="caster_link"/>
    <origin xyz="${-caster_xoff} 0.0 ${-(base_height+wheel_radius)/2}" rpy="0 0 0"/>
  </joint>
  <!-- imu -->
  <link name="imu_link">
    <visual>
      <geometry>
        <box size="0.06 0.03 0.03"/>
      </geometry>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <geometry>
        <box size="0.06 0.03 0.03"/>
      </geometry>
    </collision>
    <!-- 慣性屬性 -->
    <xacro:box_inertia m="0.1" w="0.1" d="0.1" h="0.1"/>
  </link>
  <!-- imu關(guān)節(jié) -->
  <joint name="imu_joint" type="fixed">
    <parent link="base_link"/>
    <child link="imu_link"/>
    <origin xyz="-0.05 0 -0.055"/>
  </joint>
  <!-- imu仿真插件 -->
  <gazebo reference="imu_link">
    <sensor name="imu_sensor" type="imu">
      <plugin filename="libgazebo_ros_imu_sensor.so" name="imu_plugin">
        <ros>
          <!-- 命名空間 -->
          <!-- <namespace>/demo</namespace> -->
          <remapping>~/out:=imu</remapping>
        </ros>
        <!-- 初始方位_參考 -->
        <initial_orientation_as_reference>true</initial_orientation_as_reference>
      </plugin>
      <always_on>true</always_on>
      <!-- 更新頻率 -->
      <update_rate>100</update_rate>
      <visualize>true</visualize>
      <imu>
        <!-- 角速度 -->
        <angular_velocity>
          <x>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </x>
          <y>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </y>
          <z>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>2e-4</stddev>
              <bias_mean>0.0000075</bias_mean>
              <bias_stddev>0.0000008</bias_stddev>
            </noise>
          </z>
        </angular_velocity>
        <!-- 線性加速度 -->
        <linear_acceleration>
          <x>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </x>
          <y>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </y>
          <z>
            <noise type="gaussian">
              <mean>0.0</mean>
              <stddev>1.7e-2</stddev>
              <bias_mean>0.1</bias_mean>
              <bias_stddev>0.001</bias_stddev>
            </noise>
          </z>
        </linear_acceleration>
      </imu>
    </sensor>
  </gazebo>
  <!-- 差速驅(qū)動仿真插件 -->
  <gazebo>
    <plugin name='diff_drive' filename='libgazebo_ros_diff_drive.so'>
      <ros>
        <!-- 命名空間 -->
        <!-- <namespace>/demo</namespace> -->
      </ros>

      <!-- 左右輪子 -->
      <left_joint>left_wheel_joint</left_joint>
      <right_joint>right_wheel_joint</right_joint>

      <!-- 輪距 輪子直徑 -->
      <wheel_separation>${base_width+wheel_width}</wheel_separation>
      <!-- <wheel_separation>0.52</wheel_separation> -->
      <wheel_diameter>${wheel_radius*2}</wheel_diameter>
      <!-- <wheel_diameter>0.155</wheel_diameter> -->

      <!-- 最大扭矩 最大加速度 -->
      <max_wheel_torque>20</max_wheel_torque>
      <max_wheel_acceleration>1.0</max_wheel_acceleration>

      <!-- 輸出 -->
      <!-- 是否發(fā)布里程計 -->
      <publish_odom>true</publish_odom>
      <!-- 是否發(fā)布里程計的tf開關(guān) -->
      <publish_odom_tf>true</publish_odom_tf>
      <!-- 是否發(fā)布輪子的tf數(shù)據(jù)開關(guān) -->
      <publish_wheel_tf>true</publish_wheel_tf>

      <!-- 里程計的framed ID，最終體現(xiàn)在話題和TF上 -->
      <odometry_frame>odom</odometry_frame>
      <!-- 機(jī)器人的基礎(chǔ)frame的ID -->
      <robot_base_frame>base_link</robot_base_frame>
    </plugin>
  </gazebo>
  <!-- 雷達(dá) -->
  <link name="laser">
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <cylinder radius="0.04" length="0.04"/>
      </geometry>
    </visual>
    <!-- 慣性屬性 -->
    <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="0.125"/>
      <inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001" />
    </inertial>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <cylinder radius="0.04" length="0.04"/>
      </geometry>
    </collision>
  </link>
  <!-- 雷達(dá)關(guān)節(jié) -->
  <joint name="laser_joint" type="fixed">
    <parent link="base_link"/>
    <child link="laser"/>
    <origin xyz="0.16 0 0.078" rpy="0 0 0"/>
  </joint>

  <gazebo reference="laser">
    <sensor name="laser" type="ray">
      <always_on>true</always_on>
      <visualize>false</visualize>
      <update_rate>5</update_rate>
      <ray>
        <scan>
          <horizontal>
            <samples>360</samples>
            <resolution>1.000000</resolution>
            <min_angle>0.000000</min_angle>
            <max_angle>6.280000</max_angle>
          </horizontal>
        </scan>
        <range>
          <min>0.120000</min>
          <max>3.5</max>
          <resolution>0.015000</resolution>
        </range>
        <noise>
          <type>gaussian</type>
          <mean>0.0</mean>
          <stddev>0.01</stddev>
        </noise>
      </ray>
      <plugin name="scan" filename="libgazebo_ros_ray_sensor.so">
        <ros>
          <remapping>~/out:=scan</remapping>
        </ros>
        <output_type>sensor_msgs/LaserScan</output_type>
        <frame_name>laser</frame_name>
      </plugin>
    </sensor>
  </gazebo>
  <!-- 相機(jī) -->
  <link name="camera_link">
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="0.015 0.130 0.022"/>
      </geometry>
    </visual>
    <!-- 碰撞區(qū)域 -->
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="0.015 0.130 0.022"/>
      </geometry>
    </collision>
    <!-- 慣性屬性 -->
    <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="0.035"/>
      <inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001" />
    </inertial>
  </link>
  <!-- 相機(jī)關(guān)節(jié) -->
  <joint name="camera_joint" type="fixed">
    <parent link="base_link"/>
    <child link="camera_link"/>
    <origin xyz="0.16 0 0.11" rpy="0 0 0"/>
  </joint>
  <!-- 深度相機(jī) -->
  <link name="camera_depth_frame"/>

  <joint name="camera_depth_joint" type="fixed">
    <origin xyz="0 0 0" rpy="0 0 0"/>
    <parent link="camera_link"/>
    <child link="camera_depth_frame"/>
  </joint>
  <!-- 相機(jī)仿真 -->
  <gazebo reference="camera_depth_link">
    <sensor name="depth_camera" type="depth">
      <visualize>true</visualize>
      <update_rate>30.0</update_rate>
      <camera name="camera">
        <horizontal_fov>1.047198</horizontal_fov>
        <image>
          <width>640</width>
          <height>480</height>
          <format>R8G8B8</format>
        </image>
        <clip>
          <near>0.05</near>
          <far>3</far>
        </clip>
      </camera>
      <plugin name="depth_camera_controller" filename="libgazebo_ros_camera.so">
        <baseline>0.2</baseline>
        <alwaysOn>true</alwaysOn>
        <updateRate>0.0</updateRate>
        <frame_name>camera_depth_frame</frame_name>
        <pointCloudCutoff>0.5</pointCloudCutoff>
        <pointCloudCutoffMax>3.0</pointCloudCutoffMax>
        <distortionK1>0</distortionK1>
        <distortionK2>0</distortionK2>
        <distortionK3>0</distortionK3>
        <distortionT1>0</distortionT1>
        <distortionT2>0</distortionT2>
        <CxPrime>0</CxPrime>
        <Cx>0</Cx>
        <Cy>0</Cy>
        <focalLength>0</focalLength>
        <hackBaseline>0</hackBaseline>
      </plugin>
    </sensor>
  </gazebo>

</robot>

xacro模型文件需要轉(zhuǎn)成urdf模型文件才能使用

方法1 提前轉(zhuǎn)換：

當(dāng)前文件夾打開終端輸入：base.urdf.xacro > base.urdf生成純urdf文件。

方法2 在運(yùn)行l(wèi)aunch文件的時候自動轉(zhuǎn)，需要加入xacro解析步驟

package.xml文件內(nèi)在<test_depend>前加入：<exec_depend>xacro</exec_depend>

launch文件編寫：文章來源地址http://www.zghlxwxcb.cn/news/detail-654800.html

# 此launch文件是機(jī)器人仿真程序，包含 gazebo啟動，機(jī)器人仿真生成，機(jī)器人模型狀態(tài)發(fā)布
import os
from launch import LaunchDescription
from launch.actions import ExecuteProcess
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare
from launch.substitutions import LaunchConfiguration
import xacro

def generate_launch_description():
    robot_name_in_model = 'jtbot'         #機(jī)器人模型名字
    package_name = 'jtbot_description'    #模型包名

    ld = LaunchDescription()
    use_sim_time = LaunchConfiguration('use_sim_time', default='true')
    pkg_share = FindPackageShare(package=package_name).find(package_name) 
    gazebo_world_path = os.path.join(pkg_share, 'world/jt.world')        #世界仿真文件路徑
    default_rviz_config_path = os.path.join(pkg_share, 'rviz/mrviz2.rviz')  #rviz配置文件路徑
    urdf_xacro_file = os.path.join(pkg_share, 'urdf/jtbot_base.urdf.xacro') #xacro模型文件路徑
    #解析xacro模型文件
    doc = xacro.parse(open(urdf_xacro_file))
    xacro.process_doc(doc)
    params = {'robot_description': doc.toxml()}

    # 開啟ros Gazebo server
    start_gazebo_cmd = ExecuteProcess(
        cmd=['gazebo',
        '--verbose', 
        gazebo_world_path,
        '-s', 'libgazebo_ros_init.so',   
        '-s', 'libgazebo_ros_factory.so', 
         
         ],
        output='screen')

     # Start Robot State publisher
    start_robot_state_publisher_cmd = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        output='screen',
        
        parameters=[params,{'use_sim_time': use_sim_time}]
    )    

    # gazebo內(nèi)生成機(jī)器人
    spawn_entity_cmd = Node(
        package='gazebo_ros', 
        executable='spawn_entity.py',
        arguments=['-entity', robot_name_in_model,  '-topic', 'robot_description'], 
        output='screen'
      
        )
	
   

    # Launch RViz
    start_rviz_cmd = Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', default_rviz_config_path]
        )

    ld.add_action(start_gazebo_cmd)
    ld.add_action(spawn_entity_cmd)
    ld.add_action(start_robot_state_publisher_cmd)
    ld.add_action(start_rviz_cmd)


    return ld

到了這里，關(guān)于xacro機(jī)器人模型文件轉(zhuǎn)urdf文件怎么編寫launch文件啟動gazebo仿真和在rviz2內(nèi)顯示模型的文章就介紹完了。如果您還想了解更多內(nèi)容，請在右上角搜索TOY模板網(wǎng)以前的文章或繼續(xù)瀏覽下面的相關(guān)文章，希望大家以后多多支持TOY模板網(wǎng)！