凉亭模型不成立

Question

很长的帖子很抱歉。 我创建了以下xacro文件，当使用以下启动文件加载到凉亭中时，机器人无法直立并跌落。 对于不同的链接，我尝试使用不同的质量值，但是没有运气。 好像我缺少什么，有人可以帮忙吗？

<?xml version="1.0" ?>

<robot xmlns:xacro="http://www.ros.org/wiki/xacro" 
    xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
        xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
        xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
    name="rosbot_v1">

<!--Formula for calculation of mass moment of inertia of a cylinder
is given by the following formula:
Reference: http://www.amesweb.info/SectionalPropertiesTabs/Mass-Moment-of-Inertia-Cylinder.aspx
Mass moment of inertia about x axis     Ix  Ix= (m/12) * (3r^2+h^2)
Mass moment of inertia about y axis     Iy  Iy= (m/12) * (3r^2+h^2)
Mass moment of inertia about z axis     Iz  Iz= (mr2)/2-->

<xacro:macro name="inertial_matrix_cylinder" params="mass arm_radius arm_length">
               <inertial>
                       <mass value="${mass}" />
                       <inertia ixx="${mass*(3*arm_radius*arm_radius+arm_length*arm_length)/12}" 
                                ixy = "0" ixz = "0"
                                iyy="${mass*(3*arm_radius*arm_radius+arm_length*arm_length)/12}" iyz = "0"
                                izz="${mass*arm_radius*arm_radius/2}" />
               </inertial>
</xacro:macro>

<!--Physical attributes definition for base box-->

<xacro:property name="base_box_length" value="1" />
<xacro:property name="base_box_width" value="1" />
<xacro:property name="base_box_height" value="0.6" />
<xacro:property name="base_box_mass" value="4" />

<!--Physical attributes definition for the swivel arm-->
<xacro:property name="swivel_arm_length" value="0.2" />
<xacro:property name="swivel_arm_radius" value="0.2" />
<xacro:property name="swivel_arm_mass" value="1" />

<!--Physical attributes definition for the arms-->
<xacro:property name="arm_length" value="1" />
<xacro:property name="arm_radius" value="0.1" />
<xacro:property name="arm_mass" value="0.1" />

<!--Physical attributes definition for gripper box-->
<xacro:property name="gripper_box_length" value="0.5" />
<xacro:property name="gripper_box_width" value="0.4" />
<xacro:property name="gripper_box_height" value="0.2" />
<xacro:property name="gripper_box_mass" value="0.01" />

<!--Physical attributes definition for gripper fingers-->
<xacro:property name="gripper_finger_length" value="0.12" />
<xacro:property name="gripper_finger_width" value="0.4" />
<xacro:property name="gripper_finger_height" value="0.12" />
<xacro:property name="gripper_finger_mass" value="0.001" />

<!--Formula for calculation of mass moment of inertia of a cuboid
is given by the following formula: a=x(length); b=y(width)
Mass moment of inertia about x axis     Ix  Ix= (M/12) * a^2
Mass moment of inertia about y axis     Iy  Iy= (M/12) * b^2
Mass moment of inertia about z axis     Iz  Iz= (1/12)*M*(a^2+b^2)-->

<xacro:macro name="inertial_matrix_cuboid" params="mass box_length box_width">
               <inertial>
                       <mass value="${mass}" />
                       <inertia ixx="${mass/12*(box_length*box_length)}" 
                                ixy = "0" ixz = "0"
                                iyy="${mass/12*(box_width*box_width)}" iyz = "0"
                                izz="${mass/12*(box_length*box_length + box_width*box_width)}" />
               </inertial>
</xacro:macro>

<material name="blue">
  <color rgba="0 0 0.8 1"/>
</material>

<material name="white">
  <color rgba="1 1 1 1"/>
</material>

<material name="green">
  <color rgba="0 1 0 1"/>
</material>

<material name="cyan">
  <color rgba="0 1 1 1"/>
</material>

<!-- world link -->
<link name="base_link"/>

<link name="rosbot_base">
    <xacro:inertial_matrix_cuboid mass="${base_box_mass}" box_length="${base_box_length}" box_width="${base_box_width}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="0  0  0"/>
      <geometry>
        <box size="${base_box_length} ${base_box_width} ${base_box_height}"/>
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="0  0  0"/>
      <geometry>
        <box size="${base_box_length} ${base_box_width} ${base_box_height}"/>
      </geometry>
      <material name="blue"/>
    </visual>
</link>

<!-- base_link and its fixed joint -->
<joint name="joint_fix" type="fixed">
    <parent link="base_link"/>
    <child link="rosbot_base"/>
</joint>

<!-- A swiveling base on which next arm will sit -->
<link name="rosbot_swivel_base">
    <xacro:inertial_matrix_cylinder mass="${swivel_arm_mass}" arm_length="${swivel_arm_length}" arm_radius="${swivel_arm_radius}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="0   0  ${swivel_arm_length/2}"/>
      <geometry>
        <cylinder length="${swivel_arm_length}" radius="${swivel_arm_radius}"/>
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="0   0  ${swivel_arm_length/2}"/>
      <geometry>
        <cylinder length="${swivel_arm_length}" radius="${swivel_arm_radius}"/>
      </geometry>
      <material name="white"/>
    </visual>
</link>

<!-- The joint between swivel and base needs to be flush on the top face of rosbot_base  -->
<joint name="rosbot_base_swivel_joint" type="revolute">
  <parent link="rosbot_base"/>
  <child link="rosbot_swivel_base"/>
  <origin rpy="0  0  0" xyz="0  0  ${base_box_height/2}"/>
  <axis xyz="0  0  1"/>
  <limit effort="100" lower="-1.57" upper="1.57" velocity="100"/>
</joint>

<!-- A moving/manipulating arm1 -->
<link name="rosbot_arm1">
    <xacro:inertial_matrix_cylinder mass="${arm_mass}" arm_length="${arm_length}"  arm_radius="${arm_radius}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="0   0   ${arm_length/2}"/>
      <geometry>
        <cylinder length="${arm_length}" radius="${arm_radius}"/> 
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="0   0   ${arm_length/2}"/>
      <geometry>
        <cylinder length="${arm_length}" radius="${arm_radius}"/> 
      </geometry>
      <material name="blue"/>
    </visual>
</link>

<!-- The joint between swivel and arm1 needs to be at the height of swivel link  -->
<joint name="rosbot_swivel_arm1_joint" type="revolute">
  <parent link="rosbot_swivel_base"/>
  <child link="rosbot_arm1"/>
  <origin rpy="0  0  0" xyz="0  0  ${swivel_arm_length}"/>
  <axis xyz="1  0  0"/>
  <limit effort="100" lower="-1.57" upper="1.57" velocity="100"/>
</joint>

<!-- A moving/manipulating arm2 -->
<link name="rosbot_arm2">
    <xacro:inertial_matrix_cylinder mass="${arm_mass}" arm_length="${arm_length}"  arm_radius="${arm_radius}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="0   0   ${arm_length/2}"/>
      <geometry>
        <cylinder length="${arm_length}" radius="${arm_radius}"/> 
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="0   0   ${arm_length/2}"/>
      <geometry>
        <cylinder length="${arm_length}" radius="${arm_radius}"/> 
      </geometry>
      <material name="blue"/>
    </visual>
</link>

<!-- The joint between arm1 and arm2 needs to be at height of arm1  -->
<joint name="rosbot_arm1_arm2_joint" type="revolute">
  <parent link="rosbot_arm1"/>
  <child link="rosbot_arm2"/>
  <origin rpy="0  0  0" xyz="0  0  ${arm_length}"/>
  <axis xyz="1  0  0"/>
  <limit effort="100" lower="-1.57" upper="1.57" velocity="100"/>
</joint>

<!-- A gripper box, which holds the gripper joints -->
<link name="rosbot_gripper_box">
    <xacro:inertial_matrix_cuboid mass="${gripper_box_mass}" box_length="${gripper_box_length}" box_width="${gripper_box_width}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="0   0  ${gripper_box_height/2}"/>
      <geometry>
        <box size="${gripper_box_length} ${gripper_box_width} ${gripper_box_height}"/>
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="0   0  ${gripper_box_height/2}"/>
      <geometry>
        <box size="${gripper_box_length} ${gripper_box_width} ${gripper_box_height}"/>
      </geometry>
       <material name="cyan"/>
    </visual>
</link>

<!-- The joint between arm2 and gripper needs to be at height of arm2  -->
<joint name="rosbot_arm2_gripper_joint" type="revolute">
  <parent link="rosbot_arm2"/>
  <child link="rosbot_gripper_box"/>
  <origin rpy="0  0  0" xyz="0  0  ${arm_length}"/>
  <axis xyz="0  0  1"/>
  <limit effort="100" lower="-1.57" upper="1.57" velocity="100"/>
</joint>

<!-- The left gripper  -->
<link name="rosbot_lgripper">
    <xacro:inertial_matrix_cuboid mass="${gripper_finger_mass}" box_length="${gripper_finger_length}" box_width="${gripper_finger_width}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="-0.0  0.20  ${gripper_finger_height/2}"/>
      <geometry>
        <box size="${gripper_finger_length} ${gripper_finger_width} ${gripper_finger_height}"/>
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="-0.0  0.20  ${gripper_finger_height/2}"/>
      <geometry>
        <box size="${gripper_finger_length} ${gripper_finger_width} ${gripper_finger_height}"/>
      </geometry>
      <material name="green"/>
    </visual>
  </link>

<!-- The joint between gripper box and gripper needs to be at origin/slightly higher than origin of gripper box  -->
<joint name="rosbot_lgripper_joint" type="prismatic">
    <parent link="rosbot_gripper_box"/>
    <child link="rosbot_lgripper"/>
    <origin rpy="0  0  0" xyz="-0.2  0.2  0.02"/>
    <axis xyz="1  0  0"/>
    <limit effort="100" lower="0" upper="0.14" velocity="100"/>
</joint>

<!-- The right gripper  -->
<link name="rosbot_rgripper">
    <xacro:inertial_matrix_cuboid mass="${gripper_finger_mass}" box_length="${gripper_finger_length}" box_width="${gripper_finger_width}"/>
    <collision name="rosbot_collision">
      <origin rpy="0  0  0" xyz="-0.0  0.20  ${gripper_finger_height/2}"/>
      <geometry>
        <box size="${gripper_finger_length} ${gripper_finger_width} ${gripper_finger_height}"/>
      </geometry>
    </collision>
    <visual name="rosbot_visual">
      <origin rpy="0  0  0" xyz="-0.0  0.20  ${gripper_finger_height/2}"/>
      <geometry>
        <box size="${gripper_finger_length} ${gripper_finger_width} ${gripper_finger_height}"/>
      </geometry>
      <material name="green"/>
    </visual>
  </link>

<!-- The joint between gripper box and gripper needs to be at origin or slightly higher than origin of gripper box  -->
<joint name="rosbot_rgripper_joint" type="prismatic">
    <parent link="rosbot_gripper_box"/>
    <child link="rosbot_rgripper"/>
    <origin rpy="0  0  0" xyz="0.2  0.2  0.02"/>
    <axis xyz="1  0  0"/>
    <limit effort="100" lower="-0.14" upper="0" velocity="100"/>
</joint>

</robot>

当我在凉亭中编辑模型然后切换静态标志时，它似乎很稳定。

Answer 1

我可以通过将摩擦和阻尼元素添加到URDF文件中来解决此问题。

<xacro:property name="damping_value" value="10" />
<xacro:property name="friction_value" value="0.1" />

联合中该属性的用法示例如下：

<!-- The joint between swivel and base needs to be flush on the top face of rosbot_base  -->
<joint name="rosbot_base_swivel_joint" type="revolute">
  <parent link="rosbot_base"/>
  <child link="rosbot_swivel_base"/>
  <origin rpy="0  0  0" xyz="0  0  ${base_box_height/2}"/>
  <axis xyz="0  0  1"/>
  <limit effort="100" lower="-1.57" upper="1.57" velocity="100"/>
  <dynamics damping="${damping_value}" friction="${friction_value}"/>
</joint>