turtlebot_target

Make turtlebot go to the target using keyboard

Import for turtlebot

rospy : You have to import rospy to use ros
actionlib : ros package to action
move_base_msgs, nav_msgs : message file
MoveBaseAction, MoveBaseGoal : move_base for action & goal
OccupancyGrid : cartestian coordinate(might be???)

import rospy
import actionlib
from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
from nav_msgs.msg import OccupancyGrid

Import for Keyboard in Linux

import sys
import tty
import termios

Keyboard Code

def getKey():
    fd = sys.stdin.fileno()
    original_attributes = termios.tcgetattr(fd)
    try:
        tty.setraw(sys.stdin.fileno())
        ch = sys.stdin.read(1)
    finally:
        termios.tcsetattr(fd, termios.TCSADRAIN, original_attributes)
    return ch

Target & Navigation Code

movebase_client(x,y,z)
: x,y is turtlebot coordinate, z is turtlebot direction

move_base is rosservice. Not rostopic

def movebase_client(x,y,z):

   # Create an action client called "move_base" with action definition file "MoveBaseAction"
    client = actionlib.SimpleActionClient('move_base',MoveBaseAction)

   # Waits until the action server has started up and started listening for goals.
    client.wait_for_server()

   # Creates a new goal with the MoveBaseGoal constructor
    goal = MoveBaseGoal()
    goal.target_pose.header.frame_id = "map"
    goal.target_pose.header.stamp = rospy.Time.now()
   # Move 0.5 meters forward along the x axis of the "map" coordinate frame 
    goal.target_pose.pose.position.x = x
    goal.target_pose.pose.position.y = y
   # No rotation of the mobile base frame w.r.t. map frame
    goal.target_pose.pose.orientation.z = z
    goal.target_pose.pose.orientation.w = 1.0

   # Sends the goal to the action server.
    client.send_goal(goal)
   # Waits for the server to finish performing the action.
    wait = client.wait_for_result()
   # If the result doesn't arrive, assume the Server is not available
    if not wait:
        rospy.logerr("Action server not available!")
        rospy.signal_shutdown("Action server not available!")
    else:
    # Result of executing the action
        return client.get_result()