Position Control using ROS

[Pyrojambo]

I am working on a project where I need to directly command Cartesian or joint positions to a KUKA iiwa LBR 14 using ROS. These positions are calculated in C++ from force sensor readings at either 500 or 1000Hz. I have previously tried this using DirectServo and SmartServo without using a FRI connection but the movements were performed too slowly.
Is there functionality in your toolkit that allows for this?
Thanks.

[ahundt]

It is possible to control joint positions over FRI with GRL, and we've been able to command positions. Do you need specific instructions on activating FRI with GRL? Have you been able to install the driver on Sunrise and command the arm with GRL? If so activating the FRI API should be fairly simple and we can go from there. Please note the FRI feature is still a work in progress but we are happy to work with you on it.

Regarding the force and torque sensors in the arm, there are known issues with the iiwa LBR and the readings are very inaccurate. A solution to this problem has recently been published, and we'd love to support integration of it into GRL. See https://www.disneyresearch.com/publication/toward-torque-control-of-a-kuka-lbr-iiwa/ for details, the paper itself can also be downloaded at that link. Note that this would be a substantial undertaking, and if you'd like a quick-fix solution I recommend simply purchasing a force torque sensor such as those provided by robotiq or other firms and attaching it to your end effector.

[Pyrojambo]

I have installed the driver on the Sunrise controller so a brief how-to on how to use FRI with grl and which Java APIs and cpp files work together would be most useful.

I am currently using an external force sensor attached to the end eff for this project, so will be sticking with the simple option for now.

[ahundt]

Be very careful the first time you run things with the big read button handy at all times. The robot should start straight up with all joints at 0 for this test.

So you followed the following steps?
https://ahundt.github.io/grl/howto/iiwaKukaRobotSetup.html

Once those steps are all done, starting up the driver is just selecting GRL_Driver from the kuka teach pendant's application list, ensuring autonomous mode is enabled and hit play. It will sit an wait there until grl connects to it.

If you would like to test the ROS driver, you just launch the driver executable grl_kuka_ros_driver once it it built (make sure you have it enabled & building with CMake), and also make sure the robot itself is waiting for a connection. Here is the script:

Then run the kuka_ros_test_command.sh to make it move, just one joint should rotate a few degrees. You can play around and modify the script to send a variety of joint positions.

# To run a test driving the kuka iiwa into the straight up position,
# launch each of the following in separate terminals:
# roscore 
# grl_kuka_ros_driver
# rostopic pub /interaction_mode std_msgs/String "data: 'MoveArmJointServo'"
rostopic pub /joint_traj_pt_cmd trajectory_msgs/JointTrajectoryPoint "positions: [0,0,0,0,0,0,0.1]
velocities: [0,0,0,0,0,0,0]
accelerations: [0,0,0,0,0,0,0]
effort: [0,0,0,0,0,0,0]
time_from_start: {secs: 1, nsecs: 0}"

We also have a fully integrated ROS setup that works with the kuka and integrates with https://github.com/IFL-CAMP/iiwa_stack/ at:
https://github.com/cpaxton/costar_stack/

[ahundt]

Do you have any other questions?

[Pyrojambo]

Sorry, I've had to work on other things instead recently.
I'm now trying to build the grl_kuka_ros_driver.cpp using catkin_make but it doesn't build any of cpp files

[ahundt]

you need to use ccmake and set WITH_ROS=ON, then it will build the ROS node.

Alternately, you can see how it is done with cmake parameters in:
https://github.com/ahundt/robotics_setup/blob/master/grl_kuka.sh

Don't forget to put the FRI zip in the data folder or the driver won't build.

[Pyrojambo]

I'm still having issues with ccmake .. and make -j. The errors seem to come from .fbs files not building their header files.
Also the FRI zip folder I have doesn't have the two TransformationProviderApp folders, will this also be causing errors?

[ahundt]

which version of grl and sunrise are you using?

[Pyrojambo]

I am using the latest version of grl on the master branch. Sunrise version is 1.10.0.8

[ahundt]

Ah we have 1.11, and I think that might be the source of the problem. Is there any chance it might not be too difficult to upgrade?

[Pyrojambo]

I managed to get Sunrise 1.11 which solved the issues with the TransformationProviderApp folders.
But I still have issues during make -j, when it converts fbs into header files then following message appears a lot:
[ 36%] Building C++, Java, and Python header for Time.fbs
/bin/sh: 1: --gen-name-strings: not found

[ahundt]

It seems like you need to update your flatbuffers version as well. The current release is https://github.com/google/flatbuffers/tree/v1.8.0

[Pyrojambo]

It was 1.8 that I had but reinstalled it from that link and still got the same problem.
[ 13%] Building C++, Java, and Python header for Time.fbs
/bin/sh: 1: --gen-name-strings: not found
CMakeFiles/grlflatbuffers.dir/build.make:188: recipe for target 'include/grl/flatbuffer/Time_generated.h' failed
make[2]: *** [include/grl/flatbuffer/Time_generated.h] Error 127
make[2]: *** Waiting for unfinished jobs....

[ahundt]

sorry can you run with make VERBOSE=1 then I can see the actual command line commands

[Pyrojambo]

[ 73%] Building C++, Java, and Python header for LogKUKAiiwaFusionTrack.fbs
cd /home/jamie/src/grl/include/grl/flatbuffer && --gen-name-strings --scoped-enums --gen-object-api -c -j -p -o /home/jamie/src/grl/build/include/grl/flatbuffer LogKUKAiiwaFusionTrack.fbs
/bin/sh: 1: --gen-name-strings: not found
CMakeFiles/grlflatbuffers.dir/build.make:92: recipe for target 'include/grl/flatbuffer/LogKUKAiiwaFusionTrack_generated.h' failed
make[2]: *** [include/grl/flatbuffer/LogKUKAiiwaFusionTrack_generated.h] Error 127
make[2]: Leaving directory '/home/jamie/src/grl/build'
CMakeFiles/Makefile2:483: recipe for target 'CMakeFiles/grlflatbuffers.dir/all' failed
make[1]: *** [CMakeFiles/grlflatbuffers.dir/all] Error 2
make[1]: Leaving directory '/home/jamie/src/grl/build'
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2