00001 #!/usr/bin/env python 00002 # Software License Agreement (BSD License) 00003 # 00004 # Copyright (c) 2008, Willow Garage, Inc. 00005 # All rights reserved. 00006 # 00007 # Redistribution and use in source and binary forms, with or without 00008 # modification, are permitted provided that the following conditions 00009 # are met: 00010 # 00011 # * Redistributions of source code must retain the above copyright 00012 # notice, this list of conditions and the following disclaimer. 00013 # * Redistributions in binary form must reproduce the above 00014 # copyright notice, this list of conditions and the following 00015 # disclaimer in the documentation and/or other materials provided 00016 # with the distribution. 00017 # * Neither the name of the Willow Garage nor the names of its 00018 # contributors may be used to endorse or promote products derived 00019 # from this software without specific prior written permission. 00020 # 00021 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00024 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00025 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00026 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00027 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00028 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00029 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00030 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00031 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00032 # POSSIBILITY OF SUCH DAMAGE. 00033 00034 import rospy 00035 00036 import math 00037 import tf2_ros 00038 import geometry_msgs.msg 00039 import turtlesim.srv 00040 00041 if __name__ == '__main__': 00042 rospy.init_node('turtle_tf2_listener_wait') 00043 00044 tfBuffer = tf2_ros.Buffer() 00045 listener = tf2_ros.TransformListener(tfBuffer) 00046 00047 rospy.wait_for_service('spawn') 00048 spawner = rospy.ServiceProxy('spawn', turtlesim.srv.Spawn) 00049 spawner(4, 2, 0, 'turtle2') 00050 00051 turtle_vel = rospy.Publisher('turtle2/cmd_vel', geometry_msgs.msg.Twist, queue_size=1) 00052 00053 rate = rospy.Rate(10.0) 00054 while not rospy.is_shutdown(): 00055 try: 00056 trans = tfBuffer.lookup_transform('turtle2', 'turtle1', rospy.Time.now(), rospy.Duration(1.0)) 00057 except tf2_ros.Exception: 00058 continue 00059 00060 angular = 4 * math.atan2(trans.transform.translation.y, trans.transform.translation.x) 00061 linear = 0.5 * math.sqrt(trans.transform.translation.x ** 2 + trans.transform.translation.y ** 2) 00062 msg = geometry_msgs.msg.Twist() 00063 msg.linear.x = linear 00064 msg.angular.z = angular 00065 turtle_vel.publish(msg) 00066 00067 rate.sleep()