From: Erik Andresen <erik@vontaene.de>
Date: Fri, 29 Jun 2018 09:48:13 +0000 (+0200)
Subject: Added script to follow tf uwb beacon
X-Git-Url: https://defiant.homedns.org/gitweb/?a=commitdiff_plain;h=78385af76591e5fa2c228f7e53c3b7f2fc2092d6;p=ros_wild_thumper.git

Added script to follow tf uwb beacon
---

diff --git a/scripts/follow_uwb.py b/scripts/follow_uwb.py
new file mode 100755
index 0000000..cbc0be8
--- /dev/null
+++ b/scripts/follow_uwb.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python
+# -*- coding: iso-8859-15 -*-
+
+import rospy
+import tf
+import actionlib
+import tf2_ros
+import dynamic_reconfigure.client
+import numpy as np
+import thread
+from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
+from actionlib_msgs.msg import GoalStatus
+from math import *
+
+class FollowUWB:
+	def __init__(self):
+		rospy.init_node('follow_uwb')
+		rospy.on_shutdown(self.on_shutdown)
+
+		self.move_base = actionlib.SimpleActionClient("move_base", MoveBaseAction)
+		self.tfBuffer = tf2_ros.Buffer()
+		self.listener = tf2_ros.TransformListener(self.tfBuffer)
+
+		rospy.loginfo("Setting paramters")
+		self.dynreconf = dynamic_reconfigure.client.Client("/move_base/TrajectoryPlannerROS")
+		#self.dynreconf.update_configuration({'max_vel_x': 1.0, 'max_vel_theta': 1.2, 'min_in_place_vel_theta': 1.0})
+
+		rospy.loginfo("Waiting for the move_base action server to come up")
+		self.move_base.wait_for_server()
+		rospy.loginfo("Got move_base action server")
+
+	def next_pos(self, x, y):
+		rospy.loginfo("Moving to (%f, %f)" % (x, y))
+
+		# calculate angle between current position and goal
+		angle_to_goal = atan2(y, x)
+		odom_quat = tf.transformations.quaternion_from_euler(0, 0, angle_to_goal)
+
+		goal = MoveBaseGoal()
+		goal.target_pose.header.frame_id = "base_link"
+		goal.target_pose.header.stamp = rospy.Time.now()
+		goal.target_pose.pose.position.x = x
+		goal.target_pose.pose.position.y = y
+		goal.target_pose.pose.orientation.x = odom_quat[0]
+		goal.target_pose.pose.orientation.y = odom_quat[1]
+		goal.target_pose.pose.orientation.z = odom_quat[2]
+		goal.target_pose.pose.orientation.w = odom_quat[3]
+		self.move_base.send_goal(goal)
+
+		while not self.move_base.wait_for_result(rospy.Duration(1.0)) and not rospy.is_shutdown():
+			# Get the current position
+			pos = self.tfBuffer.lookup_transform("uwb_beacon", 'base_link', rospy.Time(0), rospy.Duration(2.0))
+			# Cancel if we are close enough to goal
+			if np.linalg.norm([pos.transform.translation.y, pos.transform.translation.x]) < 1:
+				rospy.loginfo("Goal within 1m, canceling")
+				self.move_base.cancel_goal()
+				return
+
+		if self.move_base.get_state() == GoalStatus.SUCCEEDED:
+			rospy.loginfo("The base moved to (%f, %f)" % (x, y))
+		else:
+			rospy.logerr("The base failed to (%f, %f). Error: %d" % (x, y, self.move_base.get_state()))
+			exit(1)
+
+	def on_shutdown(self):
+		rospy.loginfo("Canceling all goals")
+		self.move_base.cancel_all_goals()
+
+	def run(self):
+		rate = rospy.Rate(2.0)
+		while not rospy.is_shutdown():
+			# Get the current position
+			beacon_pos = self.tfBuffer.lookup_transform('base_link', "uwb_beacon", rospy.Time(0), rospy.Duration(2.0))
+			# Create a position 1m away by creating an inverse vector
+			coords_cur = (beacon_pos.transform.translation.x, beacon_pos.transform.translation.y)
+
+			# Check difference to last goal
+			if np.linalg.norm(np.array(coords_cur)) > 0.5:
+				print "Setting new goal"
+				# Set a new goal
+				thread.start_new_thread(self.next_pos, (coords_cur[0], coords_cur[1]))
+			rate.sleep()
+
+
+if __name__ == "__main__":
+	p = FollowUWB()
+	p.run()