Mission from YAML File

The Code

#! /usr/bin/env python3

from cpr_outdoornav_api_examples_lib.ros_node import RosNode
from cpr_outdoornav_api_examples_lib.yaml_config import YamlConfig
import time
import os

# The file containing the mission configuration (adjust as needed)
MISSION_YAML_FILE = os.environ.get("HOME", "administrator") + "/example_ws/src/" + \
                   "CPR-OutdoorNav/src/cpr_outdoornav_api_examples/config/sample_mission.yaml"

class MissionFromYamlFile(RosNode):
    """
    Create and run a mission loaded from a YAML configuration file.
    Be sure that your robot is within 3 meters of your first Waypoint prior to starting the mission.
    """

    def __init__(self):
        """Initialize the mission details and server connection."""

        RosNode.__init__(self, 'mission_from_yaml_file')
        self.mission = YamlConfig.yamlFileToMission(MISSION_YAML_FILE)

        # NOTE: to save the configuration to file, uncomment the following lines:
        # YamlConfig.missionToYamlFile('/tmp/test1.yaml', self.mission)

    def run(self):
        """Execute the mission."""

        if not self.mission.startMission():
            return False
        while not self.mission.isMissionComplete():
            time.sleep(1.0)
        return self.mission.getMissionSuccess()


if __name__ == '__main__':
    if MissionFromYamlFile().run():
        print("Mission completed successfully")
    else:
        print("Mission failed")

The Code Explained

Let's break down the code.

#! /usr/bin/env python3

Every Python ROS Node will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.

from cpr_outdoornav_api_examples_lib.ros_node import RosNode
from cpr_outdoornav_api_examples_lib.yaml_config import YamlConfig

We provide a library of classes that can be used within your file for ease of use. In the above example, we import the RosNode and YamlConfig classes. The RosNode class is used by all of our examples to initialize a ROS node that will execute the example mission. The YamlConfig class is used to import a YAML file and convert it to a Mission object.

MISSION_YAML_FILE = os.environ.get("HOME", "administrator") + "/example_ws/src/" + \
                   "CPR-OutdoorNav/src/cpr_outdoornav_api_examples/config/sample_mission.yaml"

This defines the file path of the YAML file that contains the mission to be executed. See the YAML file below for the example YAML file that will be executed.

class MissionFromYamlFile(RosNode):

Creates a class for your example, which inherits a RosNode object. All python mission files are requried to inherit the RosNode class.

        RosNode.__init__(self, 'mission_from_yaml_file')
        self.mission = YamlConfig.yamlFileToMission(MISSION_YAML_FILE)```

Initialize the ROS node with name mission_from_yaml_file and import the the mission from the yaml config file. The YamlConfig.yamlFileToMission() function reads teh configuration you have created in the YAML file and converts it into a Mission object.

        if not self.mission.startMission():
            return False

Upon execution of the script, the self.mission.startMission() function creates the mission client if not yet created, connects to the mission action server and sends the goal to the action server to begin the execution of the mission.

        while not self.mission.isMissionComplete():
            time.sleep(1.0)
        return self.mission.getMissionSuccess()

self.mission.isMissionComplete() monitors the mission status and only proceeds to terminating the mission has completed or been cancelled.

YAML File

The following YAML file is used in the above example mission.

mission:
  header:
    seq: 0
    stamp:
      secs: 0
      nsecs: 0
    frame_id: ''
  name: "Sample Mission"
  uuid: "8f57fd20-8a8c-4748-85ef-be1495b3ee06"
  waypoints:
    -
      name: "Waypoint: 60"
      uuid: "3edcedd7-ae0d-47cf-bd23-f7988d2779b7"
      latitude: 50.10950820165676
      longitude: -97.31898507913323
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 61"
      uuid: "ad23202e-7067-4f1c-8677-2dc07af1e729"
      latitude: 50.1095698924641
      longitude: -97.31929487427445
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 62"
      uuid: "fe452e77-4a26-41b0-b4ab-ee1859612a60"
      latitude: 50.109437123117864
      longitude: -97.31946787675591
      heading: -1.0
      tasks:
        -
          name: "Wait"
          uuid: "ec1121a8-7481-420f-b532-c47ea86afcd7"
          service_call: "/wait"
          version: "0.0.0"
          floats: [3.0]
          strings: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 63"
      uuid: "5ed54c1f-1599-497a-9c16-93c7ca6c355e"
      latitude: 50.109384820042074
      longitude: -97.3194477601883
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 64"
      uuid: "2e021345-636b-4bd3-81ba-4f6901fdc016"
      latitude: 50.10934056359333
      longitude: -97.31936192949982
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 65"
      uuid: "00c041ee-2ca4-40ba-8e38-65ac900d5a1d"
      latitude: 50.10946930962604
      longitude: -97.31921709021302
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 66"
      uuid: "a5826fc5-b696-4b63-82aa-cc2e7a426640"
      latitude: 50.10949344950718
      longitude: -97.31911382516594
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
    -
      name: "Waypoint: 67"
      uuid: "7ff204b2-79a3-46da-a8c0-2c734b4c5314"
      latitude: 50.10949613171619
      longitude: -97.31898910244675
      heading: -1.0
      tasks: []
      position_tolerance: -1.0
      yaw_tolerance: -1.0
  onav_config: "To be determined"