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 import threading
  12 from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
  13 from actionlib_msgs.msg import GoalStatus
  14 from math import *
  15
  16 class FollowUWB:
  17         def __init__(self):
  18                 rospy.init_node('follow_uwb')
  19                 rospy.on_shutdown(self.on_shutdown)
  20
  21                 self.move_base = actionlib.SimpleActionClient("move_base", MoveBaseAction)
  22                 self.tfBuffer = tf2_ros.Buffer()
  23                 self.listener = tf2_ros.TransformListener(self.tfBuffer)
  24
  25                 rospy.loginfo("Setting paramters")
  26                 self.dynreconf = dynamic_reconfigure.client.Client("/move_base/TrajectoryPlannerROS")
  27                 self.speed = None
  28                 self.__lock_set_dynreconf = threading.Lock()
  29                 self.set_speed("slow")
  30
  31                 rospy.loginfo("Waiting for the move_base action server to come up")
  32                 self.move_base.wait_for_server()
  33                 rospy.loginfo("Got move_base action server")
  34
  35         def set_speed(self, mode):
  36                 with self.__lock_set_dynreconf:
  37                         if mode == "fast" and self.speed != "fast":
  38                                 print "speed", mode
  39                                 self.dynreconf.update_configuration({'max_vel_x': 1.0, 'max_vel_theta': 1.2, 'min_in_place_vel_theta': 1.0})
  40                         elif mode == "slow" and self.speed != "slow":
  41                                 print "speed", mode
  42                                 self.dynreconf.update_configuration({'max_vel_x': 0.5, 'max_vel_theta': 1.0, 'min_in_place_vel_theta': 0.4})
  43                         self.speed = mode
  44
  45         def next_pos(self, x, y):
  46                 rospy.loginfo("Moving to (%f, %f)" % (x, y))
  47
  48                 # calculate angle between current position and goal
  49                 angle_to_goal = atan2(y, x)
  50                 odom_quat = tf.transformations.quaternion_from_euler(0, 0, angle_to_goal)
  51
  52                 goal = MoveBaseGoal()
  53                 goal.target_pose.header.frame_id = "base_link"
  54                 goal.target_pose.header.stamp = rospy.Time.now()
  55                 goal.target_pose.pose.position.x = x
  56                 goal.target_pose.pose.position.y = y
  57                 goal.target_pose.pose.orientation.x = odom_quat[0]
  58                 goal.target_pose.pose.orientation.y = odom_quat[1]
  59                 goal.target_pose.pose.orientation.z = odom_quat[2]
  60                 goal.target_pose.pose.orientation.w = odom_quat[3]
  61                 self.move_base.send_goal(goal)
  62
  63                 while not self.move_base.wait_for_result(rospy.Duration(1.0)) and not rospy.is_shutdown():
  64                         # Get the current position
  65                         pos = self.tfBuffer.lookup_transform("uwb_beacon", 'base_link', rospy.Time(0), rospy.Duration(2.0))
  66                         # Cancel if we are close enough to goal
  67                         diff = np.linalg.norm([pos.transform.translation.y, pos.transform.translation.x])
  68                         if diff < 1:
  69                                 rospy.loginfo("Goal within 1m, canceling")
  70                                 self.move_base.cancel_goal()
  71                                 return
  72
  73                         if diff > 5:
  74                                 self.set_speed("fast")
  75                         elif diff < 3:
  76                                 self.set_speed("slow")
  77
  78                 if self.move_base.get_state() == GoalStatus.SUCCEEDED:
  79                         rospy.loginfo("The base moved to (%f, %f)" % (x, y))
  80                 else:
  81                         rospy.logerr("The base failed to (%f, %f). Error: %d" % (x, y, self.move_base.get_state()))
  82                         exit(1)
  83
  84         def on_shutdown(self):
  85                 rospy.loginfo("Canceling all goals")
  86                 self.move_base.cancel_all_goals()
  87
  88         def run(self):
  89                 rate = rospy.Rate(2.0)
  90                 coords_last = (0, 0)
  91                 while not rospy.is_shutdown():
  92                         # Get the current position
  93                         beacon_pos = self.tfBuffer.lookup_transform('base_link', "uwb_beacon", rospy.Time(0), rospy.Duration(2.0))
  94                         # Create a position 1m away by creating an inverse vector
  95                         coords_cur = (beacon_pos.transform.translation.x, beacon_pos.transform.translation.y)
  96
  97                         # Check difference to last goal
  98                         if np.linalg.norm(np.array(coords_cur) - np.array(coords_last)) > 0.5:
  99                                 print "Setting new goal"
 100                                 # Set a new goal
 101                                 thread.start_new_thread(self.next_pos, (coords_cur[0], coords_cur[1]))
 102                                 coords_last = coords_cur
 103                         rate.sleep()
 104
 105
 106 if __name__ == "__main__":
 107         p = FollowUWB()
 108         p.run()