navigation for zoidberg
This package is installed using catkin_make. Clone this repository into the
catkin_workspace/src/
directory (fill in catkin_workspace with your specific catkin workspace directory). The basic instructions for making the workspace are found in the Ros tutorial. Permanently source your local catkin workspace in the home .bashrc file. For instance, if you are in you catkin_workspace home folder,
cd devel
pwd
copy the pwd output, and type
echo "source <pwd output>/setup.bash" >> ~/.bashrc
source ~/.bashrc
Once the zoiderg_nav package is in place, move to the base catkin_workspace and run catkin_make
cd catkin_workspace
catkin_make
Once installed, this package defines a number of ROS messages related to navigation and a few ROS nodes. A launch file is used to set up navigation.
roslaunch zoidberg_ros zoidberg_ros.launch
This sets up a node "helm" that sits around and waits for commands. This command will raise a fatal error if there is no Pixhawk attached to the computer.
Ubuntu sets permisions for using serial ports, and if you get an error which ends in Permission Denied, it is probably fixed by adding yourself to the group dialout.
sudo usermod -a -G dialout <username>
Username is found by clicking on the gear on the top right of the Ubuntu screen. A restart may be needed after this command to have the changes take effect.
The navigation server uses OverrideRCIn commands to actuate the robots motors. These commands will only translate to actual RC values on the RCOut channel if SYSID_MYGCS matches the Pixhawk system ID. Assuming that the Pixhawk has the default system ID of 1, check the paramter value on the Pixhawk with
rosrun mavros mavparam -n apm get SYSID_MYGCS
This can be set to 1 using the get command.
rosrun mavros mavparam -n apm set SYSID_MYGCS 1
The above commands only work if zoidberg_ros is launched and running.
Currently the script
rosrun zoidberg_ros navigation_client.py
is used to send commands. The current mission is meant to turn to a heading. If there is a Pixhawk attached, the compass is used to construct proportional RC commands. These commands can be seen to change on the rc rostopic as the pixhawk is moved.
rostopic echo /apm/rc/out
The command will exit when the desired and current heading are within a tolerance, or if the timeout is reached.