How to send WallFollow goal with rclpy

[sebastianfer]

Hi! I am currently writing code for WallFollow, but it is not working. It compiles, but I get the following error: "AssertionError: Invalid arguments passed to constructor: nsecs, secs". Any idead on how to solve it?

I am attaching both my code and the traceback from terminal if that is useful.

WALL FOLLOW:

import sys
import rclpy
from rclpy.node import Node
from rclpy.qos import qos_profile_sensor_data
 
from irobot_create_msgs.msg import HazardDetectionVector
from rclpy.action import ActionClient
from irobot_create_msgs.action import WallFollow
from builtin_interfaces.msg import Duration
         

class WallFollowActionClient(Node):
    def __init__(self):
        super().__init__('wall_follow_action_client')
        self.subscription = self.create_subscription(HazardDetectionVector, '/TonyStark/hazard_detection', self.listener_callback, qos_profile_sensor_data)
        self._action_client = ActionClient(self, WallFollow, '/TonyStark/wall_follow')
         
    def listener_callback(self, msg):
        for detection in msg.detections:
            det = detection.header.frame_id
            if det != "base_link":
               print(det)
               if det == "bump_right":
                   self.send_goal(follow_side=-1)
               elif det == "bump_left":
                   self.send_goal(follow_side=1)
               elif det == "bump_front_right":
                   self.send_goal(follow_side=-1)
               elif det == "bump_front_left":
                   self.send_goal(follow_side=1)
               elif det == "bump_front_center":
                   pass
     
                
    def send_goal(self, follow_side=1, max_runtime=5):
        print('Ready for Action')
         
        goal_msg = WallFollow.Goal()
        goal_msg.follow_side = follow_side
         
             
        goal_msg.max_runtime = Duration(seconds=5, nanoseconds=0)
         
        self._action_client.wait_for_server()
        return self._action_client.send_goal_async(goal_msg)
         
 
def main(args=None):
    rclpy.init(args=args)
     
    action_client = WallFollowActionClient()
    try:
       rclpy.spin(action_client)
    except KeyboardInterrupt:
       print('\nAction concluded')
    finally:
       print('Done')
       rclpy.shutdown()
        
        
if __name__ == '__main__':
     main()

Terminal Traceback:

bump_left
Ready for Action
Done
Traceback (most recent call last):
  File "/home/sebastian/ros2_ws/install/create3/lib/create3/wall", line 11, in <module>
    load_entry_point('create3', 'console_scripts', 'wall')()
  File "/home/sebastian/ros2_ws/build/create3/create3/wall_follow_v2.py", line 64, in main
    rclpy.spin(action_client)
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/__init__.py", line 196, in spin
    executor.spin_once()
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/executors.py", line 712, in spin_once
    raise handler.exception()
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/task.py", line 239, in __call__
    self._handler.send(None)
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/executors.py", line 418, in handler
    await call_coroutine(entity, arg)
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/executors.py", line 343, in _execute_subscription
    await await_or_execute(sub.callback, msg)
  File "/opt/ros/galactic/lib/python3.8/site-packages/rclpy/executors.py", line 107, in await_or_execute
    return callback(*args)
  File "/home/sebastian/ros2_ws/build/create3/create3/wall_follow_v2.py", line 33, in listener_callback
    self.send_goal(follow_side=1)
  File "/home/sebastian/ros2_ws/build/create3/create3/wall_follow_v2.py", line 53, in send_goal
    goal_msg.max_runtime = Duration(secs=5, nsecs=0)
  File "/opt/ros/galactic/lib/python3.8/site-packages/builtin_interfaces/msg/_duration.py", line 71, in __init__
    assert all('_' + key in self.__slots__ for key in kwargs.keys()), \
AssertionError: Invalid arguments passed to constructor: nsecs, secs

[alsora]

The name of the arguments used in the Duration constructor are wrong.
You should replace this:

goal_msg.max_runtime = Duration(seconds=5, nanoseconds=0)

with this:

goal_msg.max_runtime = Duration(sec=5, nanosec=0)

See https://docs.ros2.org/latest/api/builtin_interfaces/msg/Duration.html

[sebastianfer]

It works now. Thank you!