scripts/follow_uwb.py

   1 #!/usr/bin/env python
   2 # -*- coding: iso-8859-15 -*-
   3
   4 import rospy
   5 import tf
   6 import actionlib
   7 import tf2_ros
   8 import dynamic_reconfigure.client
   9 import numpy as np
  10 import thread
  11 from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
  12 from actionlib_msgs.msg import GoalStatus
  13 from math import *
  14
  15 class FollowUWB:
  16         def __init__(self):
  17                 rospy.init_node('follow_uwb')
  18                 rospy.on_shutdown(self.on_shutdown)
  19
  20                 self.move_base = actionlib.SimpleActionClient("move_base", MoveBaseAction)
  21                 self.tfBuffer = tf2_ros.Buffer()
  22                 self.listener = tf2_ros.TransformListener(self.tfBuffer)
  23
  24                 rospy.loginfo("Setting paramters")
  25                 self.dynreconf = dynamic_reconfigure.client.Client("/move_base/TrajectoryPlannerROS")
  26                 #self.dynreconf.update_configuration({'max_vel_x': 1.0, 'max_vel_theta': 1.2, 'min_in_place_vel_theta': 1.0})
  27
  28                 rospy.loginfo("Waiting for the move_base action server to come up")
  29                 self.move_base.wait_for_server()
  30                 rospy.loginfo("Got move_base action server")
  31
  32         def next_pos(self, x, y):
  33                 rospy.loginfo("Moving to (%f, %f)" % (x, y))
  34
  35                 # calculate angle between current position and goal
  36                 angle_to_goal = atan2(y, x)
  37                 odom_quat = tf.transformations.quaternion_from_euler(0, 0, angle_to_goal)
  38
  39                 goal = MoveBaseGoal()
  40                 goal.target_pose.header.frame_id = "base_link"
  41                 goal.target_pose.header.stamp = rospy.Time.now()
  42                 goal.target_pose.pose.position.x = x
  43                 goal.target_pose.pose.position.y = y
  44                 goal.target_pose.pose.orientation.x = odom_quat[0]
  45                 goal.target_pose.pose.orientation.y = odom_quat[1]
  46                 goal.target_pose.pose.orientation.z = odom_quat[2]
  47                 goal.target_pose.pose.orientation.w = odom_quat[3]
  48                 self.move_base.send_goal(goal)
  49
  50                 while not self.move_base.wait_for_result(rospy.Duration(1.0)) and not rospy.is_shutdown():
  51                         # Get the current position
  52                         pos = self.tfBuffer.lookup_transform("uwb_beacon", 'base_link', rospy.Time(0), rospy.Duration(2.0))
  53                         # Cancel if we are close enough to goal
  54                         if np.linalg.norm([pos.transform.translation.y, pos.transform.translation.x]) < 1:
  55                                 rospy.loginfo("Goal within 1m, canceling")
  56                                 self.move_base.cancel_goal()
  57                                 return
  58
  59                 if self.move_base.get_state() == GoalStatus.SUCCEEDED:
  60                         rospy.loginfo("The base moved to (%f, %f)" % (x, y))
  61                 else:
  62                         rospy.logerr("The base failed to (%f, %f). Error: %d" % (x, y, self.move_base.get_state()))
  63                         exit(1)
  64
  65         def on_shutdown(self):
  66                 rospy.loginfo("Canceling all goals")
  67                 self.move_base.cancel_all_goals()
  68
  69         def run(self):
  70                 rate = rospy.Rate(2.0)
  71                 while not rospy.is_shutdown():
  72                         # Get the current position
  73                         beacon_pos = self.tfBuffer.lookup_transform('base_link', "uwb_beacon", rospy.Time(0), rospy.Duration(2.0))
  74                         # Create a position 1m away by creating an inverse vector
  75                         coords_cur = (beacon_pos.transform.translation.x, beacon_pos.transform.translation.y)
  76
  77                         # Check difference to last goal
  78                         if np.linalg.norm(np.array(coords_cur)) > 0.5:
  79                                 print "Setting new goal"
  80                                 # Set a new goal
  81                                 thread.start_new_thread(self.next_pos, (coords_cur[0], coords_cur[1]))
  82                         rate.sleep()
  83
  84
  85 if __name__ == "__main__":
  86         p = FollowUWB()
  87         p.run()