ChickenSoup's profile - activity

Hi all,

I want to set the initial joint positions of a robot in gazebo simulator starting with paused physics. I used the following in the launch file.

  <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
        args="-urdf -model ps -param robot_description -J joint1 1.5 -J joint2 0.75 -J joint3 -0.5"/>

also I tried,

<node pkg="rosservice" type="rosservice" name="resetter"
                args="call --wait /gazebo/set_model_configuration '{model_name: ps, urdf_param_name: robot_description, joint_names: [joint1, joint2, joint3], joint_positions: [1.5, 0.75, -0.5]}'" />

without the -J option in urdf_spawner. Neither seems to work. Currently I have not implemented any controllers for the joints. Therefore, disabling controllers as in this need not be considered for the time being. I could see the following messages but still the joint angles have not changed.

[INFO] [WallTime: 1397641007.444278] [0.000000] Waiting for service /gazebo/set_model_configuration
[INFO] [WallTime: 1397641007.445439] [0.000000] Calling service /gazebo/set_model_configuration
[INFO] [WallTime: 1397641007.446698] [0.000000] Set model configuration status: SetModelConfiguration: success

The only way I could get it to work is by calling:

rosservice call /gazebo/set_model_configuration '{model_name: ps, urdf_param_name: robot_description, joint_names: [joint1, joint2, joint3], joint_positions: [1.5, 0.75, -0.5]}'

separately before I unpause physics.

I use ROS-Hydro with Gazebo 1.9

Any help would be really appreciated. Thanks

Hi all,

I have some questions about combining odometry with IMU for a rover navigating on a terrain.

1) (not necessarily related to ROS) What is the standard method to combine IMU and odometry for a uneven terrain rover?

• Is it like, we assume a temporal plane based on IMU and use odometry data along that plane, and finally transform it to world frame?

2) In odom_estimation.cpp (robot_pose_ekf), absolute measurements are converted to relative odom measurements in horizontal plane, as well as only the yaw measurement of IMU is used.

• So, does that mean robot_pose_ekf is only for 2D navigation? The package summary mentions that it has a 6D model (3D position and 3D orientation)

Thank you for your time.

CS

Hi all,

Since URDF does not support closed loop links I closed the loop using a hidden joint:hinge in the .gazebo.xacro file for my robot, following some ROS answers for a similar question.

<gazebo>
  <joint:hinge name="${prefix}_${suffix}_parallel_hinge2">
      <body1>${link}</body1>
      <body2>${prefix}_${suffix}_wheel_HubTop</body2>
      <anchor>${prefix}_${suffix}_wheel_HubTop</anchor>
      <axis>0 1 0</axis>
      <anchorOffset>0 0 -0.045</anchorOffset>
  </joint:hinge>
</gazebo>

However, when I change the joint:hinge to joint:slider the model no longer has this joint in the gazebo (show joints).

<gazebo>
  <joint:slider name="${prefix}_${suffix}_parallel_hinge2">
      <body1>${link}</body1>
      <body2>${prefix}_${suffix}_wheel_HubTop</body2>
      <anchor>${prefix}_${suffix}_wheel_HubTop</anchor>
      <axis>0 1 0</axis>
      <anchorOffset>0 0 -0.045</anchorOffset>
  </joint:slider>
</gazebo>

Why is that? Any workaround? Also, joint:screw didn't work either.

Thank you

Cheers!

CS

Hi all,

I would like to get some insight about how the PR2 base controller works. Regarding the same topic, a question was raised previously with the title "PR2 base controller algorithm" but the answers do not provide adequate information.

In addition I would to like get clarified some of other questions I have:

i) when a commanding velocity is set by an external node, as in http://www.ros.org/wiki/pr2_controlle... , first the caster steer direction is changed and then the wheel velocity is applied, is that right?

ii) I could not find any position controller to change the caster steering in the pr2_base_controller2 code.

Thank you in advance

CS

Hi all,

Here is my question. If I have already installed ros-electric-desktop-full in my desktop, and if I want to work on NXT with ROS, how should I configure it? Can the steps mentioned in "http://www.ros.org/wiki/Robots/NXT/electric" be executed even if I have already installed ros-electric-desktop-full?

Thanks in advance

CS

Dear all,

http://robotics.usc.edu/ros/category/... says that a working drivable urdf model of the Pioneer2dx for gazebo/rviz is released.

How can I teleoperate a pioneer robot in a Gazebo simulation? I could visualize the pioneer robot both in gazebo and in rviz using,

roslaunch p2os_urdf pioneer3dx_urdf.launch

roslaunch p2os_urdf pioneer3dx.gazebo.launch

What should I do next?

By the way, after launching from above launch files, after few minutes, the robot automatically starts moving. Why is that?

Thank you in advance

CS

Dear ROS users,

I created a collada file of a terrain using Blender and now I want it to be included in a Gazebo .world file. How is this done?

Thanks in advance

CS

Hi guys,

With the sensor_model/max_range set to 5, the points of my point cloud that are longer than 5 still get inserted in the map. e.g. the max readings from the LRF

What does sensor_model/max_range really mean? Do I have to filter the LRF max readings in individual scans before assembling it to the point cloud?

Thank you in advance

CS

Hi all,

This question is to clarify something. According to http://www.ros.org/wiki/laser_assembler the individual scans are projected into a fixed frame right? So, that means we can readily use the assembled cloud in process like octomap even when the robot is moving. I mean we do not need the robot to stop and acquire the cloud.

Is this correct?

Thanks

CS

Hi all,

This question is actually related to http://answers.ros.org/question/44732...

So, apparently the plugin works only when <bodyname>base_footprint</bodyname> and fails when a custom body name is given.

I am using ros-electric.

The error is at -> ROS_FATAL("gazebo_ros_imu plugin error: bodyName: %s does not exist\n",bodyName.c_str());

Tried debugging the plugin but with no luck. Any help would be appreciated.

Thank you

CS

Hi all,

We have some sensor data that are saved as .csv files (data+timestamp) from a robot, which does not run ROS. To run some algorithms, I converted once such file into a ROS bag file using a python script.

After setting the /use_sim_time parameter and when playback this bag file with rosbag play --clock abc.bag, all the data seems to be flushed at once.

I need to know what determines the natural play speed of a bag file. I thought it is done using the header.stamp

Thank you in advance

CS

Hello all,

I migrated from electric to fuerte and when I start my custom robot in gazebo I get the following errors. I am using the hector gazebo imu. I could not find (grep) where these errors are coming from.

Error [Param.cc:250] Parameter [headingDrift] is a [Ss], attempting to get as a double. Error [Param.cc:250] Parameter [headingGaussianNoise] is a [Ss], attempting to get as a double.

Any help would be appreciated.

Thank you

CS

Hello all,

In Gazebo simulation, the PR2 goes down a ramp due to gravity ; I assume the wheel base controller still applies 0 velocity for the wheels. How should I keep PR2 stationary? What changes should be made in the base controller, URDF, transmission?

Thanks in advance.

CS

Hi all,

As far as I understand, there is a problem with the transform of base to bottom_cam in ardrone_autonomy. The problem is as follows: In ardrone_driver.cpp around line 92~97 we see the following code.

// Bottom Cam to Base (Bad Assumption: No translation from IMU and Base)
// TODO: This should be different from Drone 1 & 2.
tf_base_bottom = tf::StampedTransform(
            tf::Transform(
                tf::createQuaternionFromRPY(180.0 * _DEG2RAD, 0.0, 90.0 * _DEG2RAD),
                tf::Vector3(0.0, -0.02, 0.0)),
            ros::Time::now(), droneFrameBase, droneFrameBottomCam
            );

1) The above rotation makes the x-axis of the bottom_cam point towards the y-axis of the ardrone_base_link while the y-axis of the bottom_cam point towards the x-axis of the ardrone_base_link. This gives trouble if the bottom_cam observe, for instance, a marker like alvar (ar_track_alvar) which is aligned with the ardrone_base_link; it makes the forward and backward reversed.

2) I guess the translation in the negative Y direction is also wrong. May be it should be in the negative Z direction from the ardrone_base_link

3) Just a minor matter: the comment should also be corrected to Base to Bottom cam (not bottom to base).

So, I suggest

tf_base_bottom = tf::StampedTransform(
            tf::Transform(
                //tf::createQuaternionFromRPY(180.0 * _DEG2RAD, 0.0, 90.0 * _DEG2RAD),
                tf::createQuaternionFromRPY(-180.0 * _DEG2RAD, 0, -90.0 * _DEG2RAD),
                //tf::Vector3(0.0, -0.02, 0.0)),
                tf::Vector3(0.0, 0.0, -0.02)),
            ros::Time::now(), droneFrameBase, droneFrameBottomCam
            );

By the way, there was a similar question at link

Thank you

CS

Hi all,

I simulate a robot in gazebo while it maps the environment using octomap_server. I have 2 questions regarding the visualization.

1) the mapped octomap cells get cleared after some time if the robot does not re-visit the area previously mapped. Why is this happenning?

2) why the colors of the octomap changing after a while?

Thank you

CS

########## Edit ##########

Running ROS-Groovy ros-groovy-octomap 1.5.4 ros-groovy-octomap-mapping 0.4.8 ros-groovy octomap-ros 0.2.6

The second image shows that areas previously filled had been removed after some time.

launch file

      <param name="resolution" value="0.2" />        
      <param name="frame_id" type="string" value="/map" />

      <!-- maximum range to integrate (speedup!) -->
      <param name="sensor_model/max_range" type="double" value="30.0" />

      <!-- data source to integrate (PointCloud2) -->
      <remap from="cloud_in" to="/snapshotter/assembled_cloud" />
      <param name="latch" type="bool" value="false" />
      <param name="height_map" type="bool" value="true" />      
      <param name="sensor_model/[hit|miss]" value="0.9 / 0.1" />

Hi all,

Can someone tell me how to configure the environment for Fuerte so that I can get my custom packages to run as before?

I am looking for something similar to this:

http://www.ros.org/wiki/ROS/Tutorials...

Thanks Cheers

CS

Hi all,

I tried running pr2 in gazebo (pr2.launch), but removing the robot_pose_ekf in "pr2_bringup.launch" plus setting the parameter "odom_frame" to "odom" (changing from odom_combined to odom) for slam_gmapping node. Also, to get the tfs from odometry I changed "publish_tf" to true in pr2_odometry.yaml (in /pr2_simulator/pr2_controller_configuration_gazebo/pr2_odometry.yaml). Actually I am changing a custom launch files not the originals.

When I visualize it in rviz, using both the fixed frame and target frame set to /odom I see the pr2 is kind of blinking (Robot Model status changing back and forth between OK and Error).

Also, in the Map field I get a status error saying that "No transform from [map] to [/odom]". Thus, the map is not aligned in the display.

What is happening here? By the way I am running ros-electric in ubuntu 11.04.

Thank you in advance

CS

Hi all,

I was wondering if anyone here has worked on a terrain robot (3D) in Gazebo simulation. What I would like to know is,

• how to write a base controller so that it can travel on inclined planes and stay still without being dragged by the gravity when it stops. --> I implemented one similar to the pr2 base controller but it cannot do the above; need some help on this

Thank you in advance

CS

@chukcha2 no i did not use RGBD SLAM after all.

Hi all,

As far as I understand, RGBD SLAM uses visual features in addition to the point cloud to perform SLAM. If I use a tilting LRF, which has high resolution and range than a kinect, can I use RGBD SLAM package (probably with some modification) to do just point cloud SLAM without using any visual features?

Thanks in advance

CS

@tonybaltovski ok I understand. So, what modifications should I make to compile and upload to DUE as in link text

Hello all,

What is the board name I should use for BOARD? The following does not work.

generate_arduino_firmware(due_project
  SRCS due_project.cpp ${ROS_LIB_DIR}/time.cpp
  BOARD due
  PORT /dev/ttyACM0
)

I have installed DUE related stuff in IDE by Tools -> Boards Manager. I just want the arduino things to be built using catkin just like other packages. Also, I noticed that /home/peshala/arduino-1.6.5-r5/hardware/arduino/avr/boards.txt does not contain an entry for "due".

Thank you.

CS

Hi all,

Can someone tell what happens in "iterativeLeastSquares" method in http://mirror.umd.edu/roswiki/doc/api...

According to its description the function is used to compute the most likely solution to the odometry using iterative least squares. And, I tried understanding the code but with no luck.

If someone can give a rough idea, then I would be able to follow the code.

Thank you

CS

file(GLOB QWT_INCLUDE_DIR "/usr/include/qwt")
include_directories(include ${catkin_INCLUDE_DIRS} ${QWT_INCLUDE_DIR})

and

file(GLOB QWT_LIBRARIES "/usr/lib/libqwt*")
target_link_libraries(<your_program> ${QT_LIBRARIES} ${catkin_LIBRARIES} ${QWT_LIBRARIES})

worked for me.

My qwt stuff were in /usr/include/qwt folder; not in /usr/include/qwt-qt4

cheers!

@Ricky Thank you very much.

Hey guys,

Is there any ROS 3D pointcloud SLAM package available, which does not use any odometry sources? http://wiki.ros.org/ethzasl_icp_mapper seems to require the sensor_frame → /odom transform.

Thanks.

actually I am not talking about visual odometry. I am looking for package that only makes use of pointcloud data, for example from a Velodyne sensor, and perform 3D SLAM. Thanks!

After connecting to VLP16, connect to the web server at http://192.168.1.201/ and you will find settings to change many hardware settings. There you can change the return mode.

more details: http://velodynelidar.com/lidar/hdldow...

cheers