tf_publisher

#!/usr/bin/env python
#
# This script looks for a particular tf transformation
# and publish it as a TransformStamped topic.
# This may be useful to insert tf frames into dynamic-graph
# through dynamic_graph_bridge.
#

import logging

import rospy

import tf
import geometry_msgs.msg


def main():
    rospy.init_node("tf_publisher", anonymous=True)

    frame = rospy.get_param("~frame", "")
    childFrame = rospy.get_param("~child_frame", "")
    topic = rospy.get_param("~topic", "")
    rateSeconds = rospy.get_param("~rate", 5)

    if not frame or not childFrame or not topic:
        logging.error("frame, childFrame and topic are required parameters")
        return

    rate = rospy.Rate(rateSeconds)
    tl = tf.TransformListener()
    pub = rospy.Publisher(topic, geometry_msgs.msg.TransformStamped)

    transform = geometry_msgs.msg.TransformStamped()
    transform.header.frame_id = frame
    transform.child_frame_id = childFrame

    ok = False
    while not rospy.is_shutdown() and not ok:
        try:
            tl.waitForTransform(childFrame, frame, rospy.Time(), rospy.Duration(0.1))
            ok = True
        except tf.Exception:
            logging.warning("waiting for tf transform")
            ok = False

    while not rospy.is_shutdown():
        time = tl.getLatestCommonTime(frame, childFrame)
        (p, q) = tl.lookupTransform(childFrame, frame, time)
        transform.header.seq += 1
        transform.header.stamp = time

        transform.transform.translation.x = p[0]
        transform.transform.translation.y = p[1]
        transform.transform.translation.z = p[2]

        transform.transform.rotation.x = q[0]
        transform.transform.rotation.y = q[1]
        transform.transform.rotation.z = q[2]
        transform.transform.rotation.w = q[3]

        pub.publish(transform)
        rate.sleep()


main()