shenhaobin's profile - activity

The URDF simply describes the kinematic and dynamic properties of your robot mechanism. If you want to make a joint rotate a specific angle, you need to write a controller that commands the joint to do something. The controller will probably monitor the joint position, and command joint efforts or velocities. See the robot mechanism controllers wiki page for examples of controllers that run in the pr2 controller infrastructure.

It's possible the dynamic damping is way too large. Try setting it to 0

    <dynamics damping="0.0" friction="0.0"/>

Given that the gravity effects are turned off, the arms should not move when you start up simulation.

Also, try setting <selfCollide> tags to false in case your collision geometries are in collision with each other

    <selfCollide>false</selfCollide>

Friction has no effect at this time.

hi,everyone. I went to simulate my robot arm in gazebo.Here is my urdf file.

<robot name="jixiebi1">
  <link name="base_link">
    <visual>
      <geometry>
        <box size="1.5 1 0.2"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0.1"/>
      <material name="blue">
        <color rgba="0 0 .8 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <box size="1.5 1 0.2"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0.1"/>
    </collision>
    <inertial>
      <mass value="200"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>
  <joint name="base_link-arm1-11" type="fixed">
    <parent link="base_link"/>
    <child link="arm1-11"/>
    <origin rpy="0 0 0" xyz="0 0 0.2"/>
  </joint>
    <link name="arm1-11">
        <visual>
            <geometry>
                <mesh filename="arm - arm1.STL"/>
            </geometry>
            <origin rpy="0 0 0" xyz="0 0 0"/>
            <material name="arm1-11_color">
                <color rgba="0.752941 0.752941 0.752941 1"/>
            </material>
        </visual>
        <collision>
            <geometry>
                <mesh filename="arm - arm1.STL"/>
            </geometry>
            <origin rpy="0 0 0" xyz="0 0 0"/>
        </collision>
        <inertial>
            <mass value="1.04075"/>
            <inertia ixx="0.004368" ixy="-0.00001" ixz="0.000002" iyy="0.004367" iyz="-0.000001" izz="0.002456"/>
            <origin rpy="0 0 0" xyz="0.000393 -0.000373 -0.074418"/>
        </inertial>
    </link>
    <joint name="arm1-11-arm2-11" type="continuous">
        <limit effort="1000.0" lower="-3.1415926" upper="3.1415926" velocity="0.5"/>
        <dynamics damping="1000.0" friction="1000.0"/>
        <parent link="arm1-11"/>
        <child link="arm2-11"/>
        <origin rpy="0 0 0" xyz="0 0 0.172"/>
        <axis xyz="0 0 1"/>
    </joint>
    <link name="arm2-11">
        <visual>
            <geometry>
                <mesh filename="arm - arm2.STL"/>
            </geometry>
            <origin rpy="0 0 0" xyz="0 0 0.0"/>
            <material name="arm2-11_color">
                <color rgba="0.752941 0.752941 0.752941 1"/>
            </material>
        </visual>
        <collision>
            <geometry>
                <mesh filename="arm - arm2.STL"/>
            </geometry>
            <origin rpy="0 0 0" xyz="0 0 0.0"/>
        </collision>
        <inertial>
            <mass value="1.26789"/>
            <inertia ixx="0.003947" ixy="-0.000001" ixz="-0.000617" iyy="0.006723" iyz="-0.000004" izz="0.005568"/>
            <origin rpy="0 0 0" xyz="-0.100667 0.000085 -0.013708"/>
        </inertial>
    </link>
    <gazebo reference="base_link">
        <material>Gazebo/GrassFloor</material>
        <turnGravityOff>false</turnGravityOff>
        <selfCollide>true</selfCollide>
    </gazebo>
    <gazebo reference="arm1-11">
        <mu1>100</mu1>
        <mu2>100</mu2>
        <material>Gazebo/White</material>
        <turnGravityOff>true</turnGravityOff>
        <selfCollide>true</selfCollide>
    </gazebo>
    <gazebo reference="arm2-11">
        <mu1>100</mu1>
        <mu2>100</mu2>
        <material>Gazebo/White</material>
        <turnGravityOff>true</turnGravityOff>
        <selfCollide>true</selfCollide>
    </gazebo>
</robot>

When I ran the urdf file, I found the arm2-11 link turn around arm1-11 link. I went to know is there any way to make the arm2-11 link static in begin running.

simmechanics_to_urdf is desiged to save a lot of work when creating a URDF file for a complex robot, but it does not do everything. Definitely check out this tutorial. Also, before moving into gazebo, I would ensure that your model looks right and moves correctly in rviz first.

I want to create my own robot model and simulate that with C or C++ code through gazebo. First I create my own robot model by Solidwork software and export the model to xml and STl files by using the plug-in SimMechanics Link. Then I transformed urdf fil from the xml file by the simmechanics_to_urdf packet. my code likes below:

rosrun simmechanics_to_urdf convert.py jixiebi.xml xml > jixiebi.urdf

After that, I copy all of the STL files to the catalog of /simulator_gazebo/gazebo_worlds/Media/models. Finally,I run the below code

rosrun gazebo spawn_model -file `pwd`/jixiebi.urdf -urdf -z 1 -model my_jixiebi

and now I can see my model. But the model goes to mess. I guess it's the coordinate error, but I don't know how to deal with. I know the urdf has origin tag but I find it's very difficult to fix all link's and joint's coordinate correctly. What's worse, my model has hundreds of links and joints. So, here is my questions.

1. Is there any wrongs in my process?
2. How to deal with my problem?
3. If the mess model problem could figure out, the next step is how to do?

Thanks a lot and look forward to your answer.