pytroller

Python controller generator for ros2_control.

Usage

Generate the controller package using :

$ ros2 pytroller create my_pytroller --destination-directory controllers

The raw Python controller logic script my_pytroller_logic_impl.py to be implemented is located the script directory inside the newly created controller package.

This Python script containing the definition of the pytroller_logic_impl function that takes as input

• state : type dict {joint/interface, value} : current joint states on all available interfaces
• commands : type dict {joint/interface, value} : commands to be assigned to joint command interfaces
• msg : command message from subscriber
• params : type dict {parameter, value} : node parameters

For example :

# my_pytroller/script/my_pytroller_logic_impl.py

from math import cos, sin

def pytroller_logic_impl(period, states, commands, msg, params):

  commands['joint1/effort'.encode('ascii')] = msg.data[0]
  commands['joint2/effort'.encode('ascii')] = msg.data[1]

  return commands

Install all dependencies and build the controller using

$ rosdep install --ignore-src --from-paths . -y -r
$ colcon build

Parameters

Pytrollers use parameters generated by the generate_parameter_library package and are defined in the my_pytroller_parameters.yaml file :

my_pytroller:
  interface_full_names: {
    type: string_array,
    default_value: [],
    description: "Full names of the interface(s) to command",
  }
  command_topic_name: {
    type: string,
    default_value: ""  # "~/commands",
    description: "Name of the subscribed command topic"
  }
  command_topic_type: {
    type: string,
    default_value: ""  # "std_msgs/msg/Float64MultiArray",
    description: "Type of the subscribed command topic"
  }

Additional parameters can be added to this configuration file. To do so, refer to the generate_parameter_library package documentation.

The values of the defined parameters are set in the controller configuration file used for ros2-control.

Contacts

ICube Laboratory, University of Strasbourg, France

Maciej Bednarczyk: mcbed.robotics@gmail.com, @github: mcbed