example_nav_to_pose.py

#! /usr/bin/env python3
# Copyright 2021 Samsung Research America
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
 
from geometry_msgs.msg import PoseStamped
from nav2_simple_commander.robot_navigator import BasicNavigator, TaskResult
import rclpy
from rclpy.duration import Duration
 
"""
Basic navigation demo to go to pose.
"""
 
 
def main():
    rclpy.init()
 
    navigator = BasicNavigator()
 
    # Set our demo's initial pose
    initial_pose = PoseStamped()
    initial_pose.header.frame_id = 'map'
    initial_pose.header.stamp = navigator.get_clock().now().to_msg()
    initial_pose.pose.position.x = 0.0
    initial_pose.pose.position.y = 0.0
    initial_pose.pose.orientation.z = 0.0
    initial_pose.pose.orientation.w = 1.0
    navigator.setInitialPose(initial_pose)
 
    # Activate navigation, if not autostarted. This should be called after setInitialPose()
    # or this will initialize at the origin of the map and update the costmap with bogus readings.
    # If autostart, you should `waitUntilNav2Active()` instead.
    # navigator.lifecycleStartup()
 
    # Wait for navigation to fully activate, since autostarting nav2
    navigator.waitUntilNav2Active()
 
    # If desired, you can change or load the map as well
    # navigator.changeMap('/path/to/map.yaml')
 
    # You may use the navigator to clear or obtain costmaps
    # navigator.clearAllCostmaps()  # also have clearLocalCostmap() and clearGlobalCostmap()
    # global_costmap = navigator.getGlobalCostmap()
    # local_costmap = navigator.getLocalCostmap()
 
    # Go to our demos first goal pose
    goal_pose = PoseStamped()
    goal_pose.header.frame_id = 'map'
    goal_pose.header.stamp = navigator.get_clock().now().to_msg()
    goal_pose.pose.position.x = 17.86
    goal_pose.pose.position.y = -0.77
    goal_pose.pose.orientation.w = 1.0
    goal_pose.pose.orientation.z = 0.0
 
    # sanity check a valid path exists
    # path = navigator.getPath(initial_pose, goal_pose)
 
    go_to_pose_task = navigator.goToPose(goal_pose)
 
    i = 0
    while not navigator.isTaskComplete(task=go_to_pose_task):
        
 
        # Do something with the feedback
        i = i + 1
        feedback = navigator.getFeedback(task=go_to_pose_task)
        if feedback and i % 5 == 0:
            print(
                'Estimated time of arrival: '
                + '{:.0f}'.format(
                    Duration.from_msg(feedback.estimated_time_remaining).nanoseconds
                    / 1e9
                )
                + ' seconds.'
            )
 
            print(
                'Distance remaining: '
                + '{:.2f}'.format(feedback.distance_remaining)
                + ' meters.'
            )
 
            print(
                'Position error: '
                + '{:.2f}'.format(feedback.position_tracking_error)
                + ' meters.'
            )
 
            print(
                'Heading error: '
                + '{:.2f}'.format(feedback.heading_tracking_error)
                + ' radians.'
            )
 
            # Some navigation timeout to demo cancellation
            if Duration.from_msg(feedback.navigation_time) > Duration(seconds=600.0):
                navigator.cancelTask()
 
            # Some navigation request change to demo preemption
            if Duration.from_msg(feedback.navigation_time) > Duration(seconds=18.0):
                goal_pose.pose.position.x = 0.0
                goal_pose.pose.position.y = 0.0
                go_to_pose_task = navigator.goToPose(goal_pose)
 
    # Do something depending on the return code
    result = navigator.getResult()
    if result == TaskResult.SUCCEEDED:
        print('Goal succeeded!')
    elif result == TaskResult.CANCELED:
        print('Goal was canceled!')
    elif result == TaskResult.FAILED:
        (error_code, error_msg) = navigator.getTaskError()
        print('Goal failed!{error_code}:{error_msg}')
    else:
        print('Goal has an invalid return status!')
 
    navigator.lifecycleShutdown()
 
    exit(0)
 
 
if __name__ == '__main__':
    main()