AttributeError: 'list' object has no attribute 'header'

Question

I'm trying to create a client to send a goal to the move_group server via Python.

Here is my code snippet:

client = actionlib.SimpleActionClient('move_group', moveit_msgs.msg.MoveGroupAction)

client.wait_for_server()
    
MoveGroupGoal = moveit_msgs.msg.MoveGroupGoal()

start_state_ = moveit_msgs.msg.RobotState()
start_state_.joint_state = [0, 1.2, 0, 0.2, 0, -0.8, 0]
MoveGroupGoal.request.start_state = start_state_

posestamped = geometry_msgs.msg.PoseStamped()
posestamped.header.frame_id = "base_link"
posestamped.pose.orientation.w = 0.025
posestamped.pose.orientation.x = 0.0
posestamped.pose.orientation.y = 1.0
posestamped.pose.orientation.z = 0.0
posestamped.pose.position.x = 0.3
posestamped.pose.position.y = 0.0
posestamped.pose.position.z = 0.8

tolerance_position = 0.1
tolerance_orientation = 0.1

constraint_goal = moveit.core.kinematic_constraints.constructGoalConstraints(
    "tool0", posestamped, tolerance_position, tolerance_orientation)

MoveGroupGoal.request.goal_constraints = constraint_goal

client.send_goal(MoveGroupGoal)

client.wait_for_result()

return client.get_result()

Before running the above code, the demo.launch in the MoveIt package has been launched.

However, when the program executed to line client.send_goal(MoveGroupGoal), I met the following error

  File "/opt/ros/noetic/lib/python3/dist-packages/actionlib/simple_action_client.py", line 92, in send_goal
    self.gh = self.action_client.send_goal(goal, self._handle_transition, self._handle_feedback)
  File "/opt/ros/noetic/lib/python3/dist-packages/actionlib/action_client.py", line 561, in send_goal
    return self.manager.init_goal(goal, transition_cb, feedback_cb)
  File "/opt/ros/noetic/lib/python3/dist-packages/actionlib/action_client.py", line 466, in init_goal
    self.send_goal_fn(action_goal)
  File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 882, in publish
    self.impl.publish(data)
  File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 1066, in publish
    serialize_message(b, self.seq, message)
  File "/opt/ros/noetic/lib/python3/dist-packages/rospy/msg.py", line 152, in serialize_message
    msg.serialize(b)
  File "/home/xzc/mambaforge/envs/robostackenv/lib/python3.9/site-packages/moveit_msgs/msg/_MoveGroupActionGoal.py", line 917, in serialize
    buff.write(_get_struct_6d3I().pack(_x.goal.request.workspace_parameters.min_corner.x, _x.goal.request.workspace_parameters.min_corner.y, _x.goal.request.workspace_parameters.min_corner.z, _x.goal.request.workspace_parameters.max_corner.x, _x.goal.request.workspace_parameters.max_corner.y, _x.goal.request.workspace_parameters.max_corner.z, _x.goal.request.start_state.joint_state.header.seq, _x.goal.request.start_state.joint_state.header.stamp.secs, _x.goal.request.start_state.joint_state.header.stamp.nsecs))
AttributeError: 'list' object has no attribute 'header'

Did I miss the definitions of some messages?

Thanks in advance!

Answer 1

joint_state should be a sensor_msgs/JointState msg not a list. If you search for "header" in the error msg you can see that it is trying to serialize the header in the joint state msg which doesn't exist because you passed a list. _x.goal.request.start_state.joint_state.header.stamp.secs