- Way to publish to control gazebo husky (press Tab as much as you can)
rostopic pub /husky_velocity_controller/cmd_vel geometry_msgs/Twist -r 100 '[0.5,0,0]' '[0,0,0]' - Need to rebuild and resource when codes get changed
- If the program can't find something (eg., .world file), look at the launch file, use roscd to find correct path and put it there
- yaml file: mind the format and the way to write topic name (/scan with "/")
- .hpp: include essential header files(msgs, C++ libraries, etc)
- .cpp:
- callback: use -> for vector
- CORRECT WAY to write a subscriber and do some processing in callback function
- .launch: rosparam format
- Use RViz to visualize stuffs is better in Gazebo
- Check the exact value of the members in sensor_msgs/LaserScan, it might not be what you imagined.
- Need to adjust control gain to get good performance.
- CORRECT WAY to write a publisher.
- Another publisher
- Include headers for message
- Compute using angle and distance, remember to use correct tf link to visualize in Gazebo
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Make sure how nodes communicate by looking at their subs and pubs, and looking at topics as well
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To launch ekf node, need to load parameters from somewhere. In this example it's in husky_control package
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To use rqt_multiplot more efficiently, one can save the configuration file and load it directly next time
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For time, if anything in gazebo is loaded(eg., a world), the time will be set to use_sim_time. otherwise this should be set in the launch file by
``` <param name="use_sim_time" value="true"/> ```
And be sure to add --clock while playing rosbag
```
rosbag play data.bag --clock
```
- For husky visualization in RViz, because it's not loaded via gazebo, we need to do 2 things
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Add a robot_state_publisher node in the launch file(If you notice that there's already /ekf_localization_node publishing to /tf topic. Here's one explanation: because frame and husky config info is not complete only by /ekf's publications)
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" /> -
Husky's configuration need to be written in launch file. Do this by imitating spawn_husky.launch. Namely, these lines:
<arg name="husky_gazebo_description" default="$(optenv HUSKY_GAZEBO_DESCRIPTION)"/> <arg name="laser_enabled" default="true"/> <arg name="ur5_enabled" default="false"/> <arg name="kinect_enabled" default="false"/> <param name="robot_description" command="$(find xacro)/xacro.py '$(arg husky_gazebo_description)' laser_enabled:=$(arg laser_enabled) ur5_enabled:=$(arg ur5_enabled) kinect_enabled:=$(arg kinect_enabled) " />
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Implemented a service server to send bool info to a topic, /start_stop to control manual stop of husky
rosservice call /emergency_stop "data: true" -
Implemented a service client to communicate with service server, send command from the client and receive feedback as an addition.
rosrun husky_highlevel_controller husky_highlevel_controller_client 1 // for start, anything other than 1 for stop -
Because there are more than one executables now, need to do a lot of modifications to CMakeLists.txt, especially in
- find_package
- add_executable
- target_link_libraries
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Need to modify package.xml accordingly
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Created a subs in Husky node to enable/disable husky by sending controller real signals or a constant
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Corresponding publ is in service server, as it's running all the time
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Don't know why but ROS_DEBUG_MESSAGE only shows while calling service server in console
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Didn't write client in launch file now. Can be done in future or add this in other parts of the program(automatic stop)
- https://www.ethz.ch/content/dam/ethz/special-interest/mavt/robotics-n-intelligent-systems/rsl-dam/ROS2017/exercise5.pdf
- https://github.com/fairlight1337/ros_service_examples/blob/master/CMakeLists.txt
- http://docs.ros.org/jade/api/std_srvs/html/srv/SetBool.html
- https://www.ethz.ch/content/dam/ethz/special-interest/mavt/robotics-n-intelligent-systems/rsl-dam/ROS2017/lecture4.pdf
- http://wiki.ros.org/ROS/Tutorials/ExaminingServiceClient