ROS 2 Driver for AR4 Now Available

That looks awesome, I'm not familiar with ROS/ROS2, would this run on a light client like a Pi ?

Also, does your driver also control the nano/gripper ?

I wanted to mention that Yifei Cheng has added files for the MK2 to this repo. I have not had time to test yet but I was hoping someone in the comunity would be able to test this out on the MK2 and give feedback. I also wanted to thank Yifei for taking the time to put this together and contributing to the project. This is a great development - Thank you.

@jacob  it would be great if you can test it!

Update: AR4 servo gripper control has been added!

Great work ! Thanks a lot. My AR4 is now ROS2 controlled. Calibration works, path planning and execution using MoveIt works well. I'm stuck with the hand-eye validation. Intel camera is detected and I see the video in MoveIt. Hand-eye calibration is ok, I took 6 samples, aruco tag is detected. When I try to run the hand-eye validation procedure, the aruco tag is detected but planning fails. with the following message: "unable to sample any valid states for goal tree" Any idea why ??

When using the driver I often have issues with path tolerance being violated, halting the robots movment and causing problems, this especially happens for joints 3 and 4, do you run into this problem? When the controllers.yaml file in ar_hardware_interface is updated it seems the new values are not used, and it continues to use a tolerance of .200.

I have tested this with the MK3, looks very promising and works. We are still working with @ycheng517 on calibration details, my joints are a little off.

Any chance this works with the AR-3?

My use of it has gone in fits and starts, and I'm back to it now. I never got ROS Melodic fully implemented, and now it's so old it's starting to lose compatibility with new equipment like the depth and tracking cameras I'm trying to use...

wow! that's great!

I'm looking for a URDF file (for MK3, a simple one, just with the joints and limitations) - I saw you have something xarco), but I didnt see any regular urdf. do you have something similar by any chance (and I'm completely newbe, so it might be that I simply didnt see it...) thanks!!

Hey Yifei!

Firstly, thank you very much for all your effort on this. Second, do you have any recommendations on how to 'calibrate & commission' the arm to a user's unique implementation? For example, in the instructions that Chris Annin gives for the AR4-MK3, the commissioning procedure verifies that the motors and encoders are going the right direction, and that the limit switches are acting correctly. I ask this because when I started up the arm today after getting ROS2 working through WSLg, with calibrate:=True the arm started moving in an unexpected way, so I turned off the power. I investigated in RVIZ and the encoders are causing correct movements on some joints, and opposite on others.

Any hints would be appreciated!

I am currently working on bringing up the AR4 MK3 system with ROS 2 Humble and would like to confirm the exact versions being used to ensure compatibility and debug alignment.

Could you please provide me with the following:

1. The specific version or commit hash of the AR4 driver code you are currently using.
2. The ROS 2 distribution and version that the AR4 driver has been tested with.
3. The Arduino sketch version or last updated date for the Teensy controlling the AR4.
4. The working example of xacro file

Having these details will help me align my environment precisely with your tested configuration, ensuring a smoother debugging and integration process.

Thank you in advance for your assistance.

colcon build

Starting >>> annin_ar4_description

Finished <<< annin_ar4_description [0.88s]

Starting >>> annin_ar4_driver

Starting >>> annin_ar4_moveit_config

Finished <<< annin_ar4_moveit_config [0.90s]

--- stderr: annin_ar4_driver

/home/ravi/ar4_ros_driver_bkkk/annin_ar4_driver/src/ar_servo_gripper_hw_interface.cpp: In member function ‘virtual hardware_interface::CallbackReturn annin_ar4_driver::ARServoGripperHWInterface::on_init(const hardware_interface::HardwareInfo&)’:

/home/ravi/ar4_ros_driver_bkkk/annin_ar4_driver/src/ar_servo_gripper_hw_interface.cpp:21:14: error: ‘struct hardware_interface::HardwareInfo’ has no member named ‘limits’

21 | if (!info_.limits.empty()) {

| ^~

/home/ravi/ar4_ros_driver_bkkk/annin_ar4_driver/src/ar_servo_gripper_hw_interface.cpp:22:41: error: ‘struct hardware_interface::HardwareInfo’ has no member named ‘limits’

22 | for (const auto& limitpair : info.limits) {

| ^~

gmake[2]: [CMakeFiles/annin_ar4_driver.dir/build.make:90: CMakeFiles/annin_ar4_driver.dir/src/ar_servo_gripper_hw_interface.cpp.o] Error 1

gmake[2]: Waiting for unfinished jobs....

gmake[1]: [CMakeFiles/Makefile2:139: CMakeFiles/annin_ar4_driver.dir/all] Error 2

gmake: [Makefile:146: all] Error 2

---

Failed <<< annin_ar4_driver [9.12s, exited with code 2]

Summary: 2 packages finished [10.5s]

1 package failed: annin_ar4_driver

1 package had stderr output: annin_ar4_driver

1 package not processed

I was getting this error while building main branch, I just blocked that part and continue , is that an issue?

hi Yifei Cheng 
I am wondering if the code will work out of the box with a setup running the newer AR4 6.3 controller software. Given that the microstepping is altert via the dip switches, I assume the teensy code from your ros2-repo would also need some changes?

hi Yifei Cheng ,
I am aware of that and have been using your script before updating to the new official ar4 software release 6. as it comes with a change in the micro step settings I was specifically wondering if the teensy code you provide is working with the new settings or if one would have to roll-back to the micro-step settings from the older instructions??