zero joint velocities or zero effort from gazebo_ros

[jacknlliu]

For some robots in ros repos, joint_state_controller and gazebo_ros_joint_state_publisher can't publish non-zero velocity in topic /joint_states when we use the Position hardware interface in simualtion with gazebo. But for some robots like iiwa_stack, it works.

But if we use the Velocity hardware interface, it always works.

Many months ago, I comment this issue on Adding velocity to joint state publisher gazebo plugin #669. But I think this is a bug in gazebo_ros or gazebo_ros_control, not gazebo_ros_joint_state_publisher.

Ubuntu 16.04
Gazebo 7.0
ros-kinetic-gazebo-ros 2.5.14-1xenial-20180125-144821-0800
ros-kinetic-gazebo-ros-control 2.5.14-1xenial-20180125-161406-0800

Reference

• Joint velocities in gazebo are all near to zero #354
• Adding velocity to joint state publisher gazebo plugin #669
• reset /joint_states and gazebo plugins state in gazebo #27

[jacknlliu]

zero effort in topic joint_states

Reference

• JointStateController doesn't get the effort with effort_controllers/effort_joint_interface #308
• Does Joint::GetForce() return the sum of all forces on the joint?
• Joint state controller sending wrong velocities when using joint effort controller #351
• tags for gazebo_ros_control #46

[yanqingyang]

so at last how did you get the accurate joint states(position, velocity and effort) ?

[jacknlliu]

@yanqingyang you can change to use Velocity hardware interface, and it will publish the position and velocity, but effort maybe not correct.