python sending goals to the navigation stack

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Hi! Hoping it can be helpful to someone, I have wrote two posts about sending goals to the navigation stack with a Python node (with example code):

• Sending a single goal (equivalent to the C++ tutorial), here.

• Sending a sequence of goals (complete of simulation with a turtlebot robot), here.

Cheers!

The key is the imports from the move_base_msgs.msg

A simple example

import actionlib
import rospy
from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal, MoveBaseFeedback, MoveBaseResult

rospy.init_node('send_client_goal')

client = actionlib.SimpleActionClient('/move_base', MoveBaseAction)
rospy.loginfo("Waiting for move base server")
client.wait_for_server()

goal = MoveBaseGoal()
goal.target_pose.header.frame_id = 'map' 
goal.target_pose.pose.position.x = -0.063
goal.target_pose.pose.position.y = -9.035
goal.target_pose.pose.orientation.z = 0.727
goal.target_pose.pose.orientation.w = 0.686

client.send_goal(goal)
client.wait_for_result()

goal.target_pose.header.frame_id = 'map' 
goal.target_pose.pose.position.x = new value
goal.target_pose.pose.position.y = new value
goal.target_pose.pose.orientation.z = new value
goal.target_pose.pose.orientation.w = new value

client.send_goal(goal)
client.wait_for_result()

and so on you can use a loop to make it move from goal to goal also.

There are two simple ways to get valid positions and orientations for the environment you're robots in:

1. Use RViz and set the 2D pose followed the the 2D goal go back to where you launched RViz and the goal position should print out.
2. This is the simple method use: rosrun tf tf_echo /map /base_link and this will print position/orientation the entire time the robot is moving.

You can also create a feedback callback and get the result with:

client.wait_for_result()
result = client.get_result()

You can send any number of goals without creating multiple goals:

just place the client.wait_for_result() between calls

Hope this helps.