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2016-06-17 01:15:34 -0600 commented answer How to define the inertial parameters of tool0?

I am confused because tool0 supposed to be a virtual joint or a frame. It doesn't have a real body. So how to define its inertia? Or should I attach tool directly to link_6 to get a proper measurement?

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2016-06-14 01:32:40 -0600 asked a question force/torque sensor plugin y axis abnormal

I attached a long thin gun to the flange of the robot (tool0) with a fixed type joint called FTsensor_joint. Then I made the tag < provideFeedback> and < disableFixedJointLumping> true so that the plugin could measure the force and torque of FTsensor_joint. However the result is abnormal because the Y-axis value has a big noise than X-axis and Z-axis like this image description

It seems like a noise of 50HZ, but I'm not quite sure.The problem is why noise of Y-axis(force) is much bigger? And how to eliminate it? Another strange thing is when I made the tag of joint link_6-tool0 < disableFixedJointLumping> true the noise turned to be very small like this image description

but Y-axis is still abnormal and has an initial drift. Why?? The platform I am using is ROS-Indigo with Gazebo7. Thanks a lot if you answer my question!

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2016-06-11 20:59:08 -0600 asked a question How to define the inertial parameters of tool0?

I followed the tutorial of creating URDF to build a industrial robot model. I defined link "tool0" as default so that it has no parameters at all and then attached it with a "fixed" joint to the robot. But when I attached another tool to the "tool0" frame and the tool had force interaction with the environment, it failed like thisimage description

I pegged a long and thin gun into a tube and tried to lift it up. The gun and tube both had mass and inertia. The tool seemed to be detached from the flange but they were not actually seperated. I tried to modify the inertia matrix with a bigger value like 1e-1, it behaved as expected. So is this the key to my problem and how to properly define the inertial parameters including mass and inertia matrix of virtual link "tool0"?

EDIT1

My robot URDF is as follow:

<link name="link_1">...</link>
...
<link name="link_6">...</link>
<link name="tool0"/>                                               <---where I modified later
<joint name="joint_1" type="revolute">...</joint>
....
<joint name="joint_6" type="revolute">...</joint>
<joint name="link_6-tool0" type="fixed">
    <parent link="link_6"/>
    <child link="tool0"/>
    <origin xyz="0.037 0 0" rpy="0 0 0"/>
</joint>

In another URDF I define the sensor-related parts:

<link name="sensor_link">...</link>
<joint name="sensor_joint" type="fixed">
    <parent link="tool0"/>
    <child link="sensor_link"/>
    <origin xyz="0 0 0" rpy="0 0 0"/>
</joint>

<gazebo reference="sensor_joint">
    <provideFeedback>true</provideFeedback>
    <disableFixedJointLumping>true</disableFixedJointLumping>
</gazebo>
<gazebo>
 <plugin name="FTsensor_controller" filename="libgazebo_ros_ft_sensor.so">
    <updateRate>100.0</updateRate>
    <topicName>/usr/sensor_topic</topicName>
    <jointName>sensor_joint</jointName>
</plugin>   
</gazebo>

Then I include two URDF(actually XACRO) in a new one to put them together.

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2016-04-17 03:39:36 -0600 answered a question can't find specific joint when using gazebo model plugin libgazebo_ros_ft_sensor.so

I have solved this problem. See on bitbucket gazebo issue #618 and also sdformat pull request #133

2016-04-15 02:55:07 -0600 asked a question can't find specific joint when using gazebo model plugin libgazebo_ros_ft_sensor.so

I am trying to attach a Force/Torque sensor to the end-effector of an industrial robot. I think I should attach it on joint link6-tool0 to measure ft. However, I wrote whatever except for joint_1~6 in the <jointname> tag, the terminal says:

[FATAL] [1460706723.091181613, 198.988000000]: gazebo_ros_ft_sensor plugin error: jointName: link6-tool0 does not exist

usage:

<gazebo>    
    <plugin name="FTsensor_controller"    filename="libgazebo_ros_ft_sensor.so">
       <updateRate>100.0</updateRate>
       <topicName>FTsensor_topic</topicName>
       <gaussianNoise>0.0</gaussianNoise>
       <jointName>link6-tool0 </jointName>
    </plugin>    
</gazebo>

I checked gazebo_ros_ft_sensor.cpp , relative codes are as follow:

this->joint_ = this->model_->GetJoint(this->joint_name_);
   if (!this->joint_)
   {
     ROS_FATAL("gazebo_ros_ft_sensor plugin error: jointName: %s does not exist\n",this->joint_name_.c_str());
     return;
   }

Since joint_1~6 and joint link6-tool0 are defined in the same XACRO, I have no idea why the plugin can find joint_1~6 but can not find link6-tool0. It confuses me a lot. What is actually passed by the Load function of the plugin? And how can I get the ft measurement of the end-effector?

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2016-04-11 00:45:36 -0600 commented question Gazebo camera plugin rendering in wrong order on Virtual Machine

I had a similar problem with ROS-Indigo and Gazebo7 over VMWare Station. I put a camera above some blocks. The manipulator was between them and I saw it behind the blocks from the view of camera. Images may be found https://scontent-sjc2-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/12923362_445475568991755_8163782330722924106_n.jpg?oh=da1089a0e8378c2593ceafa2fac260ad&oe=5782A773 if that can help.

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