Question about cartesian value in ex_pose_goal.py

[Averykla]

Hi author, I need to set a pre-grasp point during the robot grasping process, and then let the robot go down vertically with the posture of the pre-grasp point after the robot reaches the pre-grasp point to grasp the object. So I set the value of cartesian in your program to true during the process of the robot moving from the pre-grasp point to the grasping point. But after my test, I found that as long as I set the value of cartesian to true, my robot will move very fast. Is there any value in the program that can constrain the Cartesian path speed?

I tried cartesian_max_step, but the effect was not obvious. In addition, I would like to ask you a question. When my robot reaches the pre-grasp point, if I continue to use the original RRT planning algorithm, the robot will execute a very complex trajectory, sometimes going around in a circle and then going down to grasp the object. What path planning should I choose from the pre-grasp point to the grasping point?

[Averykla]

I read this <Added setting of cartesian speed and acceleration #53>.
I'm so Sorry, I don't have a deep understanding of MoveIt, so I still don't understand how to set the speed and acceleration values ​​of the Cartesian path.

Here is my part code of moveit.
class GetCartesianPath_Request(metaclass=Metaclass_GetCartesianPath_Request): __slots__ = [ '_header', '_start_state', '_group_name', '_link_name', '_waypoints', '_max_step', '_jump_threshold', '_prismatic_jump_threshold', '_revolute_jump_threshold', '_avoid_collisions', '_path_constraints', ]
I noticed that I don't have 'max_velocity_scaling_factor' and 'max_acceleration_scaling_factor'

OMG，I'm sorry I found my ros version is humble.So is there any way to modify the speed of a Cartesian path？

[AndrejOrsula]

Hello @Averykla,

You could try manually setting the max_cartesian_speed parameter when sending the action goal (not request). For that, you need to enable action-based execution via MoveIt2(use_move_group_action=True). However, I am not certain it works (PRs are welcome).

pymoveit2/pymoveit2/moveit2.py

Line 2221 in 60cc171

move_action_goal.request.max_cartesian_speed = 0.0

As for the ROS distribution (I see you are using Humble), pymoveit2 should automatically handle the naming changes introduced in Iron: moveit/moveit_msgs#130

pymoveit2/pymoveit2/moveit2.py

Lines 2217 to 2220 in 60cc171

	if hasattr(move_action_goal.request, "cartesian_speed_limited_link"):
	move_action_goal.request.cartesian_speed_limited_link = end_effector
	else:
	move_action_goal.request.cartesian_speed_end_effector_link = end_effector

Good luck!

[Averykla]

Hi @AndrejOrsula , I found that modifying move_action_goal.request.max_cartesian_speed = 0.0 didn't work either. I think it's probably because class GetCartesianPath_Request in ros2 humble doesn't have speed and acceleration attributes.
So, I think this may not be an easy problem.

[AndrejOrsula]

I checked, and you are correct. I took a quick look, but unfortunately, I didn't figure out the origin of the issue (internal/external). If you find it, please let us know. 🙂