机器人URDF的轮子在“滚动”时重置转向角度

Question

我目前正在尝试为我们的机器人创建一个基本的 URDF 模型（基本上是一个经过修改的移动踏板车，具有前转向 + 后轮驱动，就像汽车一样），以便在 ROS / Gazebo 中使用。

我设法让转向工作（“沿 Z 轴向左或向右转动方向盘，直到触发阈值”）。现在我假设我还需要使用“连续”类型的接头使所有轮子能够向前和向后驱动/滚动。

不幸的是，这就是我现在陷入困境的地方。 每次我转向，然后尝试更改“滚动”参数时，转向位置都会重置为零。您可以在这个模拟器中查看这一点：http://www.mymodelrobot.appspot.com（URDF代码需要放在右侧，然后点击“加载机器人URDF”，然后可以更改右上角的参数）。我只在一个轮子上尝试过（URDF 中的左前轮或“链节前轮”——我有时用德语写名字）。

我真的不知道是什么问题，我尝试了几次修改。你知道这里的问题是什么吗？

这是 URDF：

<?xml version="1.0"?>

<robot name="ben">

  <!-- * * * Link Definitions * * * -->

  <link name="basis_unten">
        <visual>
            <origin xyz="0 0 0.35" rpy="0 0 0"/>
            <geometry>
                <box size="1.70 0.66 0.50"/>
            </geometry>
            <material name="Cyan1">
                <color rgba="0.0 0.9 0.9 0.9"/>
            </material>
        </visual>   
        <collision>
            <geometry>
            <box size="2.70 0.88 0.50"/>
            </geometry>
        </collision>
    </link>

    <link name="basis_oben">
        <visual>
            <origin xyz="-0.1 0 0.84" rpy="0 0 0"/>
            <geometry>
                <box size="1.50 0.66 0.68"/>
            </geometry>
            <material name="Cyan1">
                <color rgba="0.0 0.9 0.9 0.9"/>
            </material>
        </visual>
        <collision>
            <geometry>
            <box size="2.50 0.88 0.68"/>
            </geometry>
        </collision>    
    </link>

   <link name="reifen_front_links">
        <visual>
            <origin xyz="0 0 0" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

    <link name="reifen_front_rechts">
        <visual>
            <origin xyz="0 0 0" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

    <link name="reifen_back_links">
        <visual>
            <origin xyz="-0.6 0.29 0.155" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

    <link name="reifen_back_rechts">
        <visual>
            <origin xyz="-0.6 -0.29 0.155" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

    <link name="lidar">
    <visual>
      <geometry>
        <cylinder length ="0.041" radius="0.03625"/>
      </geometry>
      <material name="lidarfarbe">
        <color rgba="0.1 0 0 1"/>

      </material>
      <origin rpy="0 0.785 0" xyz="0.8 0 1.16"/>
    </visual>
  </link>

<link name="kamera_vorne">
    <visual>
      <geometry>
        <box size="0.02 0.15 0.03"/>
      </geometry>
      <material name="kamerafarbe">
        <color rgba="0 0 1 1"/>
      </material>
      <origin rpy="0 0 0" xyz="0.77 0 1.01"/>
    </visual>
  </link>

<link name="kamera_links">
        <visual>
            <origin xyz="0.50 0.29 1.05" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

<link name="kamera_rechts">
        <visual>
            <origin xyz="0.50 -0.29 1.05" rpy="-1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

<link name="kamera_back">
        <visual>
            <origin xyz="-0.85 0 1.11" rpy="0 -1.57 0"/>
            <geometry>
                <cylinder length ="0.04" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

    <link name="ultrasonic_front_links">
        <visual>
            <origin xyz="0.75 0.29 0.5" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_front_rechts">
        <visual>
            <origin xyz="0.75 -0.29 0.5" rpy="-1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

    <link name="ultrasonic_back_links">
        <visual>
            <origin xyz="-0.75 0.29 0.5" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

    <link name="ultrasonic_back_rechts">
        <visual>
            <origin xyz="-0.75 -0.29 0.5" rpy="-1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_fresseobenl">
        <visual>
            <origin xyz="0.85 0.045 0.77" rpy="0 1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_fresseobenr">
        <visual>
            <origin xyz="0.85 -0.045 0.77" rpy="0 1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>


<link name="ultrasonic_fresseuntenl">
        <visual>
            <origin xyz="0.85 0.23 0.42" rpy="0 1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_fresseuntenr">
        <visual>
            <origin xyz="0.85 -0.23 0.42" rpy="0 1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>




<link name="ultrasonic_rueckenoben">
        <visual>
            <origin xyz="-0.85 0 0.77" rpy="0 -1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>



<link name="ultrasonic_rueckenuntenl">
        <visual>
            <origin xyz="-0.85 0.27 0.42" rpy="0 -1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenuntenm">
        <visual>
            <origin xyz="-0.85 0 0.42" rpy="0 -1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenuntenr">
        <visual>
            <origin xyz="-0.85 -0.27 0.42" rpy="0 -1.57 0"/>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<joint name="reifenlinks_joint" type="revolute">
        <parent link="basis_unten"/>
        <child link="reifen_front_links"/>
        <origin xyz="0.46 0.29 0.155" rpy="0 0 0"/>
        <axis xyz="0 0 1"/>
        <limit lower="-0.35" upper="0.35" effort="10" velocity="3"/>
    </joint>

<joint name="reifenrechts_joint" type="revolute">
        <parent link="basis_unten"/>
        <child link="reifen_front_rechts"/>
        <origin xyz="0.46 -0.29 0.155" rpy="0 0 0"/>
        <axis xyz="0 0 1"/>
        <limit lower="-0.35" upper="0.35" effort="10" velocity="3"/>
    </joint>

<link name="right_front_steering">
    <visual>
      <geometry>
        <box size ="0.01 0.01 0.01"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
    </visual>
  </link>

  <joint name="right_front_steering_to_right_front_wheel" type="continuous">
    <parent link="right_front_steering"/>
    <child link="reifen_front_links"/>
    <origin xyz="0.46 0.29 0.155"/>
    <axis   xyz="0 1 0"/>
  </joint>
</robot>

Answer 1

我从头开始完全重建了 URDF 文件，因为它非常混乱（偶然发现了其他问题），现在它可以工作了。

这是新的 URDF 供参考：

<?xml version="1.0"?>

<robot name="ben">

<!-- * * * Link Definitions * * * -->

  <!-- * * * Basis * * * -->

<link name="basis_unten">
        <visual>
            <origin xyz="0 0 0.35" rpy="0 0 0"/>
            <geometry>
                <box size="1.70 0.66 0.50"/>
            </geometry>
            <material name="Cyan1">
                <color rgba="0.0 0.9 0.9 0.9"/>
            </material>
        </visual>   
        <collision>
            <geometry>
            <box size="2.50 0.96 0.50"/>
            </geometry>
        </collision>
</link>

<link name="basis_oben">
        <visual>
            <geometry>
                <box size="1.50 0.66 0.68"/>
            </geometry>
            <material name="Cyan1">
                <color rgba="0.0 0.9 0.9 0.9"/>
            </material>
        </visual>
        <collision>
            <geometry>
            <box size="2.50 0.96 0.68"/>
            </geometry>
        </collision>    
    </link>

    <!-- * * * Reifen * * * -->

<link name="reifen_front_links">
        <visual>
            <origin xyz="0 0 0" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
</link>

<link name="reifen_front_rechts">
        <visual>
            <origin xyz="0 0 0" rpy="1.57075 0 0"/>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
</link>

<link name="reifen_back_links">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

<link name="reifen_back_rechts">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.155"/>
            </geometry>
            <material name="reifenfarbe">
                <color rgba="0 0 0 1.0"/>
            </material>
        </visual>   
    </link>

    <!-- * * * Sensorik * * * -->

<link name="lidar">
    <visual>
      <geometry>
        <cylinder length ="0.041" radius="0.03625"/>
      </geometry>
      <material name="lidarfarbe">
        <color rgba="0.1 0 0 1"/>
      </material>
    </visual>
  </link>

<link name="zed_left_camera">
        <visual>
            <origin xyz="0 0 0" rpy="0 1.57 0"/>
            <geometry>
                <cylinder radius="0.007" length=".031"/>
            </geometry>
            <material name="dark_grey">
                <color rgba="0.1 0.1 0.1 1"/>
            </material>
        </visual>
    </link>
<link name="zed_center">
        <visual>
            <origin xyz="0 0 0" rpy="0 0 0"/>
            <geometry>
                <box size="0.02 0.15 0.03"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>
    </link>
<link name="zed_right_camera">
        <visual>
            <origin xyz="0 0 0" rpy="0 1.57 0"/>
            <geometry>
                <cylinder radius="0.007" length=".031"/>
            </geometry>
            <material name="dark_grey">
                <color rgba="0.1 0.1 0.1 1"/>
            </material>
        </visual>
</link>
<link name="zed_depth_camera" />

<link name="kamera_links">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

<link name="kamera_rechts">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

<link name="kamera_back">
        <visual>
            <geometry>
                <cylinder length ="0.04" radius="0.02"/>
            </geometry>
            <material name="kamerafarbe">
                <color rgba="0 0 1 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_front_links">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_front_rechts">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_back_links">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_back_rechts">
        <visual>
            <geometry>
                <cylinder length ="0.10" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_gesichtobenl">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_gesichtobenr">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_gesichtuntenl">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_gesichtuntenr">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenoben">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenuntenl">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenuntenm">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
    </link>

<link name="ultrasonic_rueckenuntenr">
        <visual>
            <geometry>
                <cylinder length ="0.02" radius="0.02"/>
            </geometry>
            <material name="sensorfarbe">
                <color rgba="1 0 0 1"/>
            </material>
        </visual>   
</link>


<!-- * * * JOINT DEFINITIONS * * * -->

    <!-- * * * Basis * * * -->

<joint name="basis_zu_basis_oben" type="fixed">
     <origin xyz="-0.1 0 0.84" rpy="0 0 0"/>
     <parent link="basis_unten"/>
     <child link="basis_oben"/>
</joint>

    <!-- * * * Reifen Links * * * -->

<joint name="basis_zu_links_front_steering" type="revolute">
        <parent link="basis_unten"/>
        <child link="links_front_steering"/>
        <origin xyz="0.46 0.29 0.155" rpy="0 0 0"/>
        <axis xyz="0 0 1"/>
        <limit lower="-0.35" upper="0.35" effort="10" velocity="3"/>
</joint>

<link name="links_front_steering">
    <visual>
      <geometry>
        <box size =".001 .001 .001"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
    </visual>
</link>

<joint name="links_front_steering_to_reifen_front_links" type="continuous">
    <parent link="links_front_steering"/>
    <child link="reifen_front_links"/>
    <origin xyz="0.0 0.0 0.0"/>
    <axis   xyz="0 1 0"/>
</joint>

    <!-- * * * Reifen Rechts * * * -->


<joint name="basis_zu_rechts_front_steering" type="revolute">
    <parent link="basis_unten"/>
    <child link="rechts_front_steering"/>
    <origin xyz="0.46 -0.29 0.155" rpy="0 0 0"/>
    <axis xyz="0 0 1"/>
    <limit lower="-0.35" upper="0.35" effort="10" velocity="3"/>
</joint>

<link name="rechts_front_steering">
    <visual>
      <geometry>
        <box size =".001 .001 .001"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
    </visual>
</link>

<joint name="rechts_front_steering_to_reifen_front_rechts" type="continuous">
    <parent link="rechts_front_steering"/>
    <child link="reifen_front_rechts"/>
    <origin xyz="0.0 0.0 0.0"/>
    <axis   xyz="0 1 0"/>
</joint>

  <!-- * * * Reifen hinten * * * -->

<joint name="basis_zu_reifen_back_links" type="continuous">
    <parent link="basis_unten"/>
    <child link="reifen_back_links"/>
    <origin xyz="-0.6 0.29 0.155" rpy="1.57075 0 0"/>
    <axis xyz="0 0 1"/>
</joint>

<joint name="basis_zu_reifen_back_rechts" type="continuous">
    <parent link="basis_unten"/>
    <child link="reifen_back_rechts"/>
   <origin xyz="-0.6 -0.29 0.155" rpy="1.57075 0 0"/>
    <axis xyz="0 0 1"/>
</joint>

  <!-- * * * Sensorik * * * -->

<joint name="basis_zu_lidar" type="fixed">
     <parent link="basis_unten"/>
     <child link="lidar"/>
     <origin rpy="0 0.75 0" xyz="0.75 0 1.15"/>
</joint>

<joint name="basis_zu_zed_center" type="fixed">
    <parent link="basis_unten"/>
    <child link="zed_center"/>
    <origin rpy="0 0 0" xyz="0.77 0 1.01"/>
</joint>

<joint name="zed_left_camera_joint" type="fixed">
        <parent link="zed_center"/>
        <child link="zed_left_camera"/>
        <origin xyz="0 0.06 0" rpy="0 0 0" />
</joint>

<joint name="zed_depth_camera_joint" type="fixed">
        <parent link="zed_left_camera"/>
        <child link="zed_depth_camera"/>
        <origin xyz="0 0 0" rpy="-1.5707963267948966 0 -1.5707963267948966" />
</joint>

<joint name="zed_right_camera_joint" type="fixed">
        <parent link="zed_center"/>
        <child link="zed_right_camera"/>
        <origin xyz="0 -0.06 0" rpy="0 0 0" />
</joint>

<joint name="basis_zu_kamera_links" type="fixed">
    <parent link="basis_unten"/>
    <child link="kamera_links"/>
    <origin xyz="0.50 0.29 1.05" rpy="1.57075 0 0"/>
</joint>

<joint name="basis_zu_kamera_rechts" type="fixed">
    <parent link="basis_unten"/>
    <child link="kamera_rechts"/>
    <origin xyz="0.50 -0.29 1.05" rpy="-1.57075 0 0"/>
</joint>

<joint name="basis_zu_kamera_back" type="fixed">
    <parent link="basis_unten"/>
    <child link="kamera_back"/>
    <origin xyz="-0.85 0 1.11" rpy="0 -1.57 0"/>
</joint>

<joint name="basis_zu_ultrasonic_front_links" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_front_links"/>
    <origin xyz="0.75 0.29 0.5" rpy="1.57075 0 0"/>
</joint>

<joint name="basis_zu_ultrasonic_front_rechts" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_front_rechts"/>
    <origin xyz="0.75 -0.29 0.5" rpy="-1.57075 0 0"/>

</joint>

<joint name="basis_zu_ultrasonic_back_links" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_back_links"/>
    <origin xyz="-0.75 0.29 0.5" rpy="1.57075 0 0"/>
</joint>

<joint name="basis_zu_ultrasonic_back_rechts" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_back_rechts"/>
    <origin xyz="-0.75 -0.29 0.5" rpy="-1.57075 0 0"/>
</joint>

<joint name="basis_zu_ultrasonic_gesichtobenl" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_gesichtobenl"/>
    <origin xyz="0.85 0.045 0.77" rpy="1.57 1.82 0"/>
</joint>

<joint name="basis_zu_ultrasonic_gesichtobenr" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_gesichtobenr"/>
    <origin xyz="0.85 -0.045 0.77" rpy="1.57 1.32 0"/>
</joint>

<joint name="basis_zu_ultrasonic_gesichtuntenl" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_gesichtuntenl"/>
    <origin xyz="0.85 0.23 0.42" rpy="1.57 1.80 0"/>
</joint>

<joint name="basis_zu_ultrasonic_gesichtuntenr" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_gesichtuntenr"/>
    <origin xyz="0.85 -0.23 0.42" rpy="1.57 1.34 0"/>
</joint>

<joint name="basis_zu_ultrasonic_rueckenoben" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_rueckenoben"/>
    <origin xyz="-0.85 0 0.77" rpy="0 -1.57 0"/>
</joint>

<joint name="basis_zu_ultrasonic_rueckenuntenl" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_rueckenuntenl"/>
    <origin xyz="-0.85 0.27 0.42" rpy="0 -1.57 0"/>
</joint>

<joint name="basis_zu_ultrasonic_rueckenuntenm" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_rueckenuntenm"/>
    <origin xyz="-0.85 0 0.42" rpy="0 -1.57 0"/>
</joint>

<joint name="basis_zu_ultrasonic_rueckenuntenr" type="fixed">
    <parent link="basis_unten"/>
    <child link="ultrasonic_rueckenuntenr"/>
    <origin xyz="-0.85 -0.27 0.42" rpy="0 -1.57 0"/>
</joint>
</robot>