how to open/close the gripper when the arm is moving

[cncowboy]

i test throwing object in project ign_moveit2_examples, but can not open/close gripper when arm is moving! is there any method to open/close the gripper when the arm is moving ？ thanks for reply

[AndrejOrsula]

Hello. Have you tried the approach used in the example and adjusted the delay between initiating the motion and opening/closing the gripper?

Also, this repository does not provide any control interface - it is just a config for a specific robot. You probably want to consult ROS control or MoveIt documentation.

[cncowboy]

your projects is great! thanks! i runed the throw object example, it did not work exactly as the video in ign_moveit2_examples's readme, the gripper will open just after the arm reach the postion and stop for a while, even though i comment the code blow:

    # Throw itself
    joint_configuration_throw = [0.0, -0.15, 0.0, -1.1, 0.0, 1.9, 0.8]
    self._moveit2.move_to_configuration(joint_configuration_throw)

    # Release object while executing motion
    #sleep_duration_s = 1.2
    #if rclpy.ok():
    #    self.create_rate(1 / sleep_duration_s).sleep()
    self._moveit2_gripper.open()
    self._moveit2_gripper.wait_until_executed()

    self._moveit2.wait_until_executed()

besides, the gripper can only catch the throw object one time after i try many times. in my envirement, the branch of panda_ign_moveit2 is master, ros version is humble,

[AndrejOrsula]

What ROS/MoveIt distribution do you use?

[cncowboy]

in my envirement, the branch of panda_ign_moveit2 is master, ros version is humble, moveit2 version is 2.5.5, gazebo version is 11.10

[AndrejOrsula]

This repository is not made for Gazebo Classic (11.0 and older).

It was developed for the new iteration of Gazebo, which used to be called Ignition. Such as Gazebo Fortress or Garden.

[cncowboy]

Thank you for your patient guidance i reinstall gazebo to version Ignition-fortress, but the problem is not resolved

i recorded a video:

https://github.com/AndrejOrsula/panda_ign_moveit2/assets/187536/632120be-a616-4a63-9ed2-0a3b43e4cf9a

[AndrejOrsula]

Hmm, I am not sure why that would be the case. I just tried the same example in the prebuilt Docker image, and the gripper is opened while the robot is still in motion.

It might be that some dependency update from galactic to humble results in this behaviour. However, I am unable to investigate that :confused:

[cncowboy]

thanks very much! i'll try again in prebuild docker image!

[cncowboy]

could you upload your prebuild docker image to hub.docke.com,

[AndrejOrsula]

It is already there @cncowboy.

Pull the image (optional, happens automatically while running it):

docker pull andrejorsula/ign_moveit2_examples

Convenience script for running the container with NVIDIA GPU and X11 GUI (look through the script before running it):

IMAGE_NAME=andrejorsula/ign_moveit2_examples bash -c "$(wget -qO - https://gist.githubusercontent.com/AndrejOrsula/fd3971c5f26c0cc19bc9763b13142965/raw/4fa7563656829c43aaa3ad0dafc8a4cf8d609936/run.bash)"

Then you can launch the example inside the container:

ros2 launch ign_moveit2_examples ex_py_throw_object.launch.py

[cncowboy]

sorry for reply lately, because I took a few days off。 i test with docker image: andrejorsula/ign_moveit2_examples, i changed gazebo render engine to ogre because ogre2 can not render anything. then the gazebo's rendering is very slow, and the gripper throw object can not shoot success every time!

https://github.com/AndrejOrsula/panda_ign_moveit2/assets/187536/7258a01f-85d7-4944-b511-98d77e572f62

[AndrejOrsula]

... I changed gazebo render engine to ogre because ogre2 can not render anything ... then the gazebo's rendering is very slow ...

I tested everything only with an NVIDIA GPU. If you have other hardware, you might need to figure out the support yourself.

the gripper throw object can not shoot success every time!

There is some stochasticity in the simulation and how the example is implemented, so it is not expected to succeed every time.

[cncowboy]

yes, i also test with nvidia-gpu