Why is humanoid robot falling strangely using gazebo_ros_control?

asked 2021-04-03 02:24:51 -0500

kovacs.attila
1 ●1 ●2 ●1

updated 2022-06-11 10:40:03 -0500

lucasw

8729 ●137 ●239 ●256 https://github.com/lucasw

Hi guys,

I am using the following configuration:

Ubuntu 20.04
ROS Noetic
Gazebo 11.3.0

The problem is that when i run the simulation the robot falls very slowly, it takes about 20 seconds (simulation time) to fall down. Moreover it also bounces quite strangley on the floor. I've read that gazebo_ros_control package may be causing this problem but after trying different controller types as suggested, the problem persists.

Here are the controller definitions:

 # Publish all joint states -----------------------------------
joint_state_controller:
type: joint_state_controller/JointStateController
publish_rate: 50

  # Position Controllers ---------------------------------------
c1_waist_z_joint_controller:
type: effort_controllers/JointPositionController
joint: waist_z_joint
pid: {p: 1, i: 0.1, d: 0.1}

c2_waist_y_joint_controller:
type: effort_controllers/JointPositionController
joint: waist_y_joint
pid: {p: 1, i: 0.1, d: 0.1}

c3_waist_x_joint_controller:
type: effort_controllers/JointPositionController
joint: waist_x_joint
pid: {p: 1, i: 0.1, d: 0.1}

Can anyone please point me into the right direction for solving this unexpected behaviour?

Thank you in advance.

answered 2022-11-15 05:13:59 -0500

aGan
16 ●1 ●3 ●3

Are you using gazebo ros control pid_gains?

In my experienced, I saw that pid gains in ros_controllers.yaml file is useless in gazebo for now.

There is only way to use pid on gazebo you should have gazebo_ros_control parameters like below;

  gazebo_ros_control:
    pid_gains:
      J1: {p: 1000.0, i: 0.01,  d: 10.0}
      J2: {p: 1000.0, i: 0.01,  d: 10.0}
      J3: {p: 1000.0, i: 0.01,  d: 10.0}
      J4: {p: 1000.0, i: 0.01,  d: 10.0}
      J5: {p: 1000.0, i: 0.01,  d: 10.0}
      J6: {p: 1000.0, i: 0.01,  d: 10.0}

But it is hard to adjust parameters, because it is depends on your link mass and inertia. So I preferred use without pid_gains parameters . I get some error messages like below but robot is not falling.

[ INFO] [1668509415.956302590]: gazebo_ros_control plugin is waiting for model URDF in parameter [robot_description] on the ROS param server.
[ERROR] [1668509416.072938429]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J1
[ERROR] [1668509416.073647058]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J2
[ERROR] [1668509416.074322660]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J3
[ERROR] [1668509416.074994133]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J4
[ERROR] [1668509416.075751597]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J5
[ERROR] [1668509416.076452863]: No p gain specified for pid.  Namespace: /gazebo_ros_control/pid_gains/J6
[ INFO] [1668509416.080542894]: Loaded gazebo_ros_control.

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Comments

@aGan I agree that this user's problem can be fixed by setting the gazebo_ros_control "p" gains to good values.

As for your ERROR message, you should check if the property /gazebo_ros_control/pid_gains/J1/p exists on the rosparam server - you may be loading the .yaml file into the wrong namespace.

Mike Scheutzow ( 2022-11-16 07:04:38 -0500 )edit

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