Need help creating interface between my stepper motor command module (ROS topic) and MoveIt.

[Hendrik Wiese]

Hi again,

is anybody here who can help me configure my MoveIt setup in a way that it can control an arm with multiple different actuators to follow trajectories? 

Imagine an arm that is made of three Dynamixel AX-12A servos (which already work, see other threads) and a stepper motor that rotates a ball screw for linear movement. I need to know what is required to make the stepper motor follow its part of the desired end effector trajectory. As already mentioned, the Dynamixel servos work like a charm. The only thing missing is the stepper motor.

I'm already able to send the usual commands to the stepper like rotate counterclockwise with n rounds per minute or turn 3.000 steps clockwise with 30 Hz and things like that that might be relevant for trajectory movement. 

But I need help on how to create the interface between MoveIt and my command module (ROS topic).

I'd be really grateful!

Cheers,

Hendrik

[Moises Estrada]

Hi Hendrik, you need to create a controller.

Here is the theory: http://moveit.ros.org/wiki/Executing_Trajectories_with_MoveIt

But when I made my own controller I used the fake controller that is being used by default in MoveIt! and modify it to my needs, which is great for open loop control.

Here you can view the fake controller and another example: https://github.com/ros-planning/moveit_plugins

You start by modifying the "fake_execution" arg in the demo.launch:

  <include file="$(find moveit_pentaxis)/launch/move_group.launch">
    <arg name="allow_trajectory_execution" value="true"/> 
    <arg name="fake_execution" value="false"/>
    <arg name="info" value="true"/>
    <arg name="debug" value="$(arg debug)"/>
  </include>

Then you will have to create <your-robot-name>_moveit_controller_manager.launch.xml file, which is where you specify the new moveit_controller_manager and the .yaml file.

Cheers,
Moises