Franka hand force fedback

[gaspersavle]

Hi, i'm using the Franka hand on the Franka Emika Panda robot, running franka_ros on ros noetic. I control the gripper using the franka_gripper/GraspGoal message. But i've noticed that franka_gripper/joint_states effort field is always 0. I've dug into the franka_gripper_node.cpp code and i noticed that the effort is hardcoded to 0.

  ros::Publisher gripper_state_publisher =
      node_handle.advertise<sensor_msgs::JointState>("joint_states", 1);
  ros::AsyncSpinner spinner(2);
  spinner.start();
  ros::Rate rate(publish_rate);
  while (ros::ok()) {
    if (gripper_state_mutex.try_lock()) {
      sensor_msgs::JointState joint_states;
      joint_states.header.stamp = ros::Time::now();
      joint_states.name.push_back(joint_names[0]);
      joint_states.name.push_back(joint_names[1]);
      joint_states.position.push_back(gripper_state.width * 0.5);
      joint_states.position.push_back(gripper_state.width * 0.5);
      joint_states.velocity.push_back(0.0);
      joint_states.velocity.push_back(0.0);
      joint_states.effort.push_back(0.0); //these lines
      joint_states.effort.push_back(0.0); //these lines
      gripper_state_publisher.publish(joint_states);
      gripper_state_mutex.unlock();
    }
    rate.sleep();
  }

https://github.com/frankaemika/franka_ros/blob/c11f000c2737acc22ed8dfeff40555b2644a4294/franka_gripper/src/franka_gripper_node.cpp#L174-L195

Upon further inspection of LibFranka's GripperState struct i've noticed it doesn't even have an effort attribute. Is there any way to get live effort feedback from the gripper?

[AndreasKuhner]

Hi @gaspersavle ,
this issue is known and might be part of a future release - but nothing on the short term for now.

Cheers,
Andreas