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frankaemika / franka_ros

ROS integration for Franka research robots
https://frankaemika.github.io
Apache License 2.0
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[bug] Jerky movements when controlling the panda using the 'ros_control' 'joint_position/JointPositionController' #167

Open rickstaa opened 3 years ago

rickstaa commented 3 years ago

I am trying to control the real Panda robot using the joint position motion generator. I currently use the joint_position/JointPositionController controller that is found in the ros-controls/ros_control package.

Unfortunately, the control is very unstable. Although, I am able to send a control commands, the robot oscillates around the set point (see rviz visualization GIF below). I inspected the code of the franka_ros, libfranka and ros_Control packages and it looks like the ROS controller command is correctly forwarded to the robot class where it is used in the motion planner callback. My assumption therefore is that the Joint position motion generator can not handle non-smooth set-points.

It looks like my assumption is correct since sending a smooth signal, like is done in the examples you provide (i.e. https://github.com/frankaemika/franka_ros/blob/noetic-devel/franka_example_controllers/src/joint_position_example_controller.cpp and https://github.com/frankaemika/libfranka/blob/master/examples/generate_joint_position_motion.cpp) solves the oscillation issue.This is contrary to what I would have expected, namely that the motion generator would generate the motion to get the robot to a given position set point.

Is my assumption correct and can we only send smooth paths to the Joint Position motion generator, or is this a bug within my current implementation?

problem_position_control

Steps to reproduce the issue

  1. Clone this example repository.
  2. Checkout the noetic-devel-ws branch.
  3. Build the catkin workspace.
  4. Run the real_panda_position_control.launch file.
  5. Try to control the robot by publishing on the 'panda_arm_joint7_position_controller/command' topic or by using the rqt GUI.
  6. See the oscillations take place.

Extra information

The problem also appears to be happening when you set the elapsed_time_ in the joint_position_example_controller.cpp to be fixed, thereby creating a non-smooth control signal.

https://github.com/frankaemika/franka_ros/blob/356ec114c488c75edeaf5315633359459d37af31/franka_example_controllers/src/joint_position_example_controller.cpp#L66

fe-support commented 1 year ago

Closing due to inactivity. Please open this git issue again if the topic still exists.

rickstaa commented 1 year ago

Closing due to inactivity. Please open this git issue again if the topic still exists.

@fe-support, closing this issue requires verifying whether you can reproduce the problem. The last time I checked (4 months ago this issue still was present. Maybe we can re-open this issue until @frankaemika verifies it is fixed?