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Bruce Allen edited this page May 27, 2020 · 25 revisions

These notes were prepared in pre-version 1 and may no longer be relevant.

Working with uuv_simulator

  • If installed from package for ros-kinetic, roslaunch --files uuv_descriptions upload_rexrov.launch shows:

    /opt/ros/melodic/share/uuv_assistants/launch/message_to_tf.launch
/opt/ros/melodic/share/uuv_descriptions/launch/upload_rexrov_default.launch
/opt/ros/melodic/share/uuv_descriptions/launch/upload_rexrov.launch

    Rather than installing and using this package, build it from source under workspace uuv_ws.

  • When installed from our uuv_ws workspace, roslaunch --files uuv_descriptions upload_rexrov.launch shows:

    /home/bdallen/uuv_ws/src/uuv_simulator/uuv_descriptions/launch/upload_rexrov.launch
/home/bdallen/uuv_ws/src/uuv_simulator/uuv_descriptions/launch/upload_rexrov_default.launch
/home/bdallen/uuv_ws/src/uuv_simulator/uuv_assistants/launch/message_to_tf.launch

    and roslaunch --files uuv_gazebo_worlds ocean_waves.launch shows:

    /opt/ros/melodic/share/gazebo_ros/launch/empty_world.launch
/home/bdallen/uuv_ws/src/uuv_simulator/uuv_gazebo_worlds/launch/ocean_waves.launch
/home/bdallen/uuv_ws/src/uuv_simulator/uuv_assistants/launch/publish_world_ned_frame.launch

Exploring uuv_simulator

In page uuv_simulator reference we launched the ocean waves world and spawned a UUV at coordinate(0,0,-20). Here we examine the .launch files, .world files, and other code that makes this happen. Later we explore additions to this to provide a target capability: Grasp a ceramic cup.

ocean_waves.launch

Launch file ocean_waves.launch does this:

  • Include Gazebo's empty_world.launch.
  • Include uuv_assistants file publish_world_ned_frame.launch.
  • Start node publish_world_models running publish_world_models.py.
  • Optionally launch uuv_assistants file set_simulation_timer.launch.

upload_rexrov.launch

On default, starts upload_rexrov_default.launch with initial x,y,z,roll,pitch,yaw values.

empty_world.launch

This launch file, https://github.com/ros-simulation/gazebo_ros_pkgs/blob/jade-devel/gazebo_ros/launch/empty_world.launch, starts Gazebo, defining default parameters and opening /usr/share/gazebo-9/empty.world:

<?xml version="1.0" ?>
<sdf version="1.5">
  <world name="default">
    <!-- A global light source -->
    <include>
      <uri>model://sun</uri>
    </include>
    <!-- A ground plane -->
    <include>
      <uri>model://ground_plane</uri>
    </include>
  </world>
</sdf>

which defines world "default" with light and ground.

ocean_waves.launch

For launch file syntax, see http://wiki.ros.org/roslaunch.

Sensors

File ~/uuv_ws/src/uuv_simulator/uuv_assistants/templates/robot_model/urdf/sensors.xacro.template identifies example sensors: GPS, Pose 3D sensor, forward-looking sonar, DVL, RPT, Pressure, IMU, camera. See ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/*.xacro for more.

File ~/uuv_ws/src/uuv_simulator/uuv_descriptions/robots/rexrov_sonar.xacro has xacro:forward_multibeam_sonar_m450_130. It uses plugin name uuv_plugin filename libuuv_underwater_object_ros_plugin.so built from ~/uuv_ws/src/uuv_simulator/uuv_gazebo_plugins/uuv_gazebo_ros_plugins/src/UnderwaterObjectROSPlugin.cc. It connects services for modeling underwater properties.

File ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins has plugins, for example ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/include/uuv_sensor_ros_plugins/gazebo_ros_image_sonar.hh, .cpp. From CMakeLists.txt this makes image_sonar_ros_plugin.so. File image_sonar_ros_plugin.so is referenced in ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/sonar_snippets.xacro. File sonar_snippets.xacro is referenced in ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/sensor_snippets.xacro. File sensor_snippets.xacro is included from the following:

  • ~/uuv_ws/src/uuv_simulator/uuv_assistants/templates/robot_model/urdf/base.xacro.template
  • ~/uuv_ws/src/uuv_simulator/uuv_descriptions/urdf/rexrov_base.xacro
  • ~/uuv_ws/src/uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/sensor_snippets.xacro
  • ~/uuv_ws/src/uuv_simulator/uuv_tutorials/uuv_tutorial_rov_model/urdf/rov_example_base.xacro

File rexrov_base.xacro is included in several rexrov_* files, including ~/uuv_ws/src/uuv_simulator/uuv_descriptions/robots/rexrov_oberon7.xacro, which is included in the ~/uuv_ws/src/uuv_simulator/uuv_descriptions/launch/upload_rexrov_oberon7.launch file which we are using, meaning that the image_sonar_ros_plugin plugin is available in Gazebo.

Move the UUV

A systematic approach to activating the UUV.

Move from command line

  • Launch ocean waves and UUV oberon7
  • Find topics
  • Move something via a topic

Launch ocean_waves

roslaunch uuv_gazebo_worlds ocean_waves.launch

Using rosrun rqt_graph rqt_graph we see nodes /publish_world_models, /gazebo, ,world_ned_frame_publisher, and gazebo_gui. Using rostopic list we see some Gazebo topics and /hydrodynamics/current_velocity.

Launch rexrov_oberon7

roslaunch uuv_descriptions upload_rexrov_oberon7.launch mode:=default x:=0 y:=0 z:=-20 namespace:=rexrov

In rqt_graph, clicking Refresh, we see nodes /rexrov/ground_truth_to_tf_rexrov and /rexrov/robot_state_publisher. Topics between rexrov and Gazebo include /rexrov/pose_gt, /tf, /tf_static, /rexrov/joint_states.

Using rostopic list we see many /rexrov/* topics including various sensors and eight thrusters.

About the thrusters: Thruster 0 is at /rexrov/thrusters/0 and has these topics:

  • dynamic_state_efficiency
  • input
  • is_on
  • thrust
  • thrust_efficiency
  • thrust_wrench

See ~/uuv_ws/src/uuv_simulator/uuv_gazebo_plugins/uuv_gazebo_ros_plugins/src/ThrusterROSPlugin.cc and ~/uuv_ws/src/uuv_simulator/uuv_gazebo_plugins/uuv_gazebo_plugins/src/ThrusterPlugin.cc. From ThrusterPlugin.cc thrust is of type <msgs::Vector3d>. From rostopic info /rexrov/thrusters/0/thrust, it is of type uuv_gazebo_ros_plugins_msgs/FloatStamped and is published by Gazebo. Topic input is subscribed by Gazebo and is of type uuv_gazebo_ros_plugins_msgs/FloatStamped.

Move UUV using Joystick js0

Move the UUV by launching joy_accel.launch:

roslaunch uuv_control_cascaded_pid joy_accel.launch model_name:=rexrov

We can specify the Joystick ID, default joy_id:=0. This starts thruster_manager.launch and uuv_teleop.launch. The teleop uses the two joystick controls for up/down/rotate/move while the thruster manager turns these commands into thrust commands for the eight thrusters.

Move Arm

From robot_config.yaml, Oberon 7P manipulators have names: azimuth, shoulder, elbow, roll, pitch, wrist. Arm setup is in joint_effort_controllers.launch. This file is used in uuv_manipulators/oberon7/oberon7_control/launch/jt_cartesian_controller.launch and uuv_manipulators/oberon7/oberon7_control/launch/joint_control.launch. These are used in uuv_simulator/uuv_gazebo/launch/rexrov_demos/rexrov_oberon_demo.launch and uuv_simulator/uuv_gazebo/launch/rexrov_demos/rexrov_oberon_arms_demo.launch.

In looking at jt_cartesian_controller.launch and joint_control.launch, we see that joint_control.launch has arm names, so try that. See joint_control.launch for arm actuations, including gripper open/close and RB and LB deadman. Try this:

roslaunch oberon7_control joint_control.launch uuv_name:=rexrov

No, this fails: effort_controllers/JointEffortController does not exist. Note: there was no joy_id:=0 option, which seems odd.

Sonar

See files with sonar in their name. Working up from uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/src/gazebo_ros_image_sonar.cpp and uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/include/uuv_sensor_ros_plugins/gazebo_ros_image_sonar.hh we find uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/CMakeLists.txt which builds image_sonar_ros_plugin and others including rpt, imu, cpc, magnetometer, dvl, pressure, gps.

File libimage_sonar_ros_plugin.so is laded from uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/sonar_snippets.xacro which is loaded from uuv_simulator/uuv_sensor_plugins/uuv_sensor_ros_plugins/urdf/sensor_snippets.xacro. Several .xacro files load this, including uuv_simulator/uuv_descriptions/urdf/rexrov_base.xacro, which should be loaded from rexrov_oberon7.xacro.

File gazebo_ros_image_sonar.cpp plugin GazeboRosImageSonar should provide these topics:

  • point cloud points or from pointCloudTopicName, type sensor_msgs::PointCloud2
  • depth image depth/image_raw or from depthImageTopicName, type sensor_msgs::Image
  • normal image from depth image + _normals, type sensor_msgs::Image
  • multibeam image from depth image + _multibeam, type sensor_msgs::Image
  • sonar image from depth image + _sonar, type sensor_msgs::Image
  • raw sonar image from depth image + _raw_sonar, type sensor_msgs::Image
  • depth image camera info depth/camera_info or from depthImageCameraInfoTopicName

We might be interested in depth/image_sonar, emitted by calling cv::Mat GazeboRosImageSonar::ConstructVisualScanImage(cv::Mat& raw_scan). These use structures depth_image and its derivatives normal_image, multibeam_image, and raw_scan. depth_image comes from cv::Mat(height, width, CV_32FC1, (float*)_src) where CV_32FC1 is a 32-bit float 1-channel array of value _src.

Gazebo's DepthCameraPlugin.hh includes bindings for Gazebo events OnNewDepthFrame, OnNewRGBPointCloud, and OnNewImageFrame.

Using rqt_image_view

This GUI offers a list of all compatible active "camera" topics. Usage:

rosrun rqt_image_view rqt_image_view

For example /rexrov/rexrov/camera/camera_image. Unfortunately, /rexrov/dvl_sonar related topics have incompatible types. Our dvl types are:

  • /rexrov/dvl type uuv_sensor_ros_plugins_msgs/DVL
  • /rexrov/dvl_sonar0 type sensor_msgs/Range

SyllogismRXS Sonar

In paper "A Computationally-Efficient 2D Imaging Sonar Model for Underwater Robotics Simulations in Gazebo", DeMarco produces Sonar images as follows:

  1. Calculate point-cloud using angle of incidence, distance, and surface reflectivity. The reflectivity of a surface is defined by laser_retro defined in the surface's SDF file, values 0 to 255.
  2. Add Gaussian noise, transform to sonar image, add median blur, add salt-pepper noise.

File imaging_sonar_sim.cpp runs a ROS node that subscribes to a point cloud topic of type sensor_msgs::PointCloud and publishes an image of type sensor_msgs::ImagePtr which should just be a pointer to sensor_msgs::Image.

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