aruco_frame_listener.py

import rclpy
from rclpy.node import Node
from rclpy.time import Time
from std_msgs.msg import String
from tf2_ros import TransformException
from tf2_ros.buffer import Buffer
from tf2_ros.transform_listener import TransformListener

class FrameListener(Node):

    def __init__(self):
        super().__init__('stretch_tf_listener')

        self.tf_buffer = Buffer()
        self.tf_listener = TransformListener(self.tf_buffer, self)

        self.cmd_subscriber = self.create_subscription(String, 'demo_commands', self.cmd_callback, 10)

    def cmd_callback(self, msg):
        from_frame_rel = 'target_object1'
        target_frame = 'base_link'

        if msg.data == 'record_pose':
            self.get_logger().info('Got record message')
            now = Time()
            trans = self.tf_buffer.lookup_transform(
                target_frame,
                from_frame_rel,
                now)
            self.get_logger().info(f'{trans}')
        elif msg.data == 'quit':
            self.get_logger().info('Got quit message')
            self.destroy_node()
            rclpy.shutdown()


def main():
    rclpy.init()
    node = FrameListener()
    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()


if __name__ == '__main__':
    main()

keyboard_input.py

from pynput import keyboard

import rclpy
from rclpy.node import Node
from std_msgs.msg import String

class KeyboardInput(Node):
    def __init__(self):
        super().__init__('keyboard_input')
        self.publisher = self.create_publisher(String, 'demo_commands', 10)

    def publish_message(self, data):
        msg = String()
        msg.data = data
        self.publisher.publish(msg)

    def on_keyboard_press(self, key):
        if key == keyboard.Key.esc:
            self.publish_message('quit')
            self.get_logger().info('quit message sent...')
            self.destroy_node()
            rclpy.shutdown()
        if key == keyboard.Key.space:
            self.publish_message('record_pose')
            self.get_logger().info('record_pose message sent...')

    def get_keyboard_input(self):
        with keyboard.Listener(on_press=self.on_keyboard_press) as listener:
            listener.join()


if __name__ == '__main__':
    rclpy.init()
    node = KeyboardInput()
    node.get_keyboard_input()