husky wheel odom

[narutojxl]

Hello authors,
I'm using noetic-devel branch. I run roslaunch husky_gazebo husky_empty_world.launch with the default config, laser_enabled = 0, laser_secondary_enabled =0, laser_3d_enabled =0, realsense_enabled =0. I don't modify anything except I add libgazebo_ros_p3d.so into husky.urdf.xacro to get fake localization pose. When i use a logitech joystick to drive husky in gazebo empty.world, i find /husky_velocity_controller/odom topic's x and y are very different from /ground_truth/state topic's x and y position. map frame is the same with odom frame, /husky_velocity_controller/odom pose is in odom frame by default.

  <gazebo>
    <plugin name="p3d_base_controller" filename="libgazebo_ros_p3d.so">
      <alwaysOn>true</alwaysOn>
      <updateRate>20.0</updateRate>
      <bodyName>base_link</bodyName>
      <topicName>ground_truth/state</topicName>
      <gaussianNoise>0.01</gaussianNoise>
      <frameName>map</frameName>
      <xyzOffsets>0 0 0</xyzOffsets>
      <rpyOffsets>0 0 0</rpyOffsets>
    </plugin>
  </gazebo>

Then i compare vx and wz of /cmd_vel, /husky_velocity_controller/cmd_vel, /husky_velocity_controller/odom and /ground_truth/state. I find /cmd_vel, /husky_velocity_controller/cmd_vel and /husky_velocity_controller/odom are the same in vx and wz respectively. In other word, /husky_velocity_controller/odom vx is the same with gazebo received vx of /husky_velocity_controller/cmd_vel, /husky_velocity_controller/odom wz is the same with gazebo received wz of /husky_velocity_controller/cmd_vel. Please see the following two pictures, the first one is vx comparison chart, the second is wz.

My question is:

• Is /husky_velocity_controller/odom husky's wheel odom? If it is, why the velocity vx and wz is very different from the measured feedback velocity?
• Why husky does not track the received speed not well, as we see in the two chart?
• I noticed when i send a wz≠0, vx=0 on the /cmd_vel, robot in gazebo doesn't rotate in place, it does a weird go front - go back in the rotate motion, similar problem in #105 and #120. In the #PR191 , the author says

Thanks for the PR! For the Gazebo turning bug, I have noticed it too. Changing the friction didn't seem to fix it but it has been a while since I have looked into it. I'll take another look when I get a chance.

• Thanks for your any suggestions a lot!
  
  

[destogl]

Hi @narutojxl,

You probably have in the parameters of Diff Drive controller set "open_loop" to true. This ignores the feedback from hardware and publishes odometry based on the commanded velocity.

The other issue with simulation is caused by unsuitable friction parameter on the Wheels, see #191 for the adjustments.

[narutojxl]

Hello @destogl, thanks for your kind reply. I don't find open_loop param in control.yaml. In vscode, i also search with open_loop, donn't find somewhere. This is control.yaml content, is there anything i missed? I clone from husky noetic repository. I will merge #PR191 to my desktop noetic branch, thanks again:)

husky_joint_publisher:
  type: "joint_state_controller/JointStateController"
  publish_rate: 50

husky_velocity_controller:
  type: "diff_drive_controller/DiffDriveController"
  left_wheel: ['front_left_wheel', 'rear_left_wheel']
  right_wheel: ['front_right_wheel', 'rear_right_wheel']
  publish_rate: 50
  pose_covariance_diagonal: [0.001, 0.001, 0.001, 0.001, 0.001, 0.03]
  twist_covariance_diagonal: [0.0001, 0.0001, 0.0001, 0.0001, 0.0001, 0.003]
  cmd_vel_timeout: 0.25
  velocity_rolling_window_size: 2

  # Base frame_id
  base_frame_id: base_link

  # Odometry fused with IMU is published by robot_localization, so
  # no need to publish a TF based on encoders alone.
  enable_odom_tf: false

  # Husky hardware provides wheel velocities
  estimate_velocity_from_position: false

  # Wheel separation and radius multipliers
  wheel_separation_multiplier: 1.875 # default: 1.0
  wheel_radius_multiplier    : 1.0 # default: 1.0

  # Velocity and acceleration limits
  # Whenever a min_* is unspecified, default to -max_*
  linear:
    x:
      has_velocity_limits    : true
      max_velocity           : 1.0   # m/s
      has_acceleration_limits: true
      max_acceleration       : 3.0   # m/s^2
  angular:
    z:
      has_velocity_limits    : true
      max_velocity           : 2.0   # rad/s
      has_acceleration_limits: true
      max_acceleration       : 6.0   # rad/s^2

[destogl]

@narutojxl I see you are using ROS(1). Nevermind then.