how to control gen3_lite_2f gripper via ros_control

[yuweiDu]

I use ros_control for gen3_lite control. The hardware interface is used as (https://github.com/empriselab/kortex_hardware). The arm joints work well but something goes wrong with the gripper. I always get the error as:

runtime error: timeout detected: BaseClient::SendGripperCommand
Error Receiving: recvfrom() failed with error code : 104
terminate called after throwing an instance of 'std::runtime_error'
 what():  timeout detected: BaseCyclicClient::RefreshFeedback
/kortex_hardware died from signal 6
/kortex_hardware left a core dump
 Determined pattern '/tmp/rosmon-node-myw5SJ/core'
 Could not find a matching core file :-(

It seems that the error is related to BaseClient::SendGripperCommand. My OS is Ubuntu 20.04 and ROS is Noetic.

Thanks in advance for any help.

[smoya23]

Hi @yuweiDu ,

Could you provide more information on what command you ran ?

Error Receiving: recvfrom() failed with error code : 104

From the error messages, it looks like a comm issue, but I would like to try and reproduce this on my side. Are you able to reach the arm through the WebApp ? If so, can you open/close the gripper from there ?

[yuweiDu]

Hi @smoya23 ,
Yes, of course. There is something missing in the original issue I wrote. I used the hardware interface provide by @madan96 (https://github.com/empriselab/kortex_hardware) and change the "finger_joint" to "right_finger_bottom_joint" in https://github.com/empriselab/kortex_hardware/blob/4a73db42c2b23f9855051fa3c327afe67a7950be/src/Gen3Robot.cpp#L171

  hardware_interface::JointHandle grp_vel_handle(
      jnt_state_interface.getHandle("finger_joint"),
      &cmd_vel[num_full_dof - 1]);
  jnt_vel_interface.registerHandle(grp_vel_handle);

  hardware_interface::JointHandle grp_pos_handle(
      jnt_state_interface.getHandle("finger_joint"),
      &cmd_pos[num_full_dof - 1]);
  jnt_pos_interface.registerHandle(grp_pos_handle);

  hardware_interface::JointHandle grp_eff_handle(
      jnt_state_interface.getHandle("finger_joint"),
      &cmd_eff[num_full_dof - 1]);
  jnt_eff_interface.registerHandle(grp_eff_handle);

By the WebApp, I don' know where to control the gripper. But I can control the gripper by calling the service /my_gen3_lite/base/send_gripper_command. I think the connection is good here.

Thank you!

[smoya23]

@yuweiDu Are you able to run our driver and control the gripper, by launching this command?

roslaunch kortex_driver kortex_driver.launch arm:=gen3_lite dof:=6 ip_address:=<your-robot's-ip>

To control the gripper from the WebApp, you move the slider on the bottom of the page when you open either the angular or pose control menus

If you're able to control the gripper through the service, when exactly are you getting this error ? Is it happenning as soon as you're launching your launch file ?