check controller_manager status
I am using ros_control with robotis arms (github). I want to know how to check the status of the controller_manager. Because I found that even if the controller_manager dies, the write is still executed which could lead to improper data being written.
I encountered this when I used <node name="ros_control_controller_manager" pkg="controller_manager" type="controller_manager" respawn="false" output="screen" args="load pos_based_pos_traj_controller" /> in my launch file. The controller would load and then stop, but the write would be writing zero to the hardware.
So how can I overcome this problem or is this a invalid concern?
Also how do you check whether system has initialized properly, so that you can write. As when you initialize the system for the first time, I have only zeros in the position_cmd variable used to write to the hardware for certain period of time.
Not really an answer, but I've seen this kind of thing done by basically implementing a position hold, where
write(..)uses the values fromread(..)until it has received new valid values.