Does franky support controlling two Franka robots simultaneously from one machine?

[SuperFanBin]

Dear author,

First of all, thank you for developing franky—it has been a great tool for my single-arm robotic projects!

Recently, I started working on a dual-arm setup, and I’d like to continue using franky to control both Franka Emika arms from the same computer. However, I’ve encountered an issue when trying to control both robots concurrently.

Problem Description
When I run motions on both robots in the same script, the first robot to start moving exhibits unexpected disturbances or jerky behavior (as shown in this video). The issue does not occur when controlling each robot individually.

from franky import Robot, Gripper, JointWaypoint, JointWaypointMotion

def move_home_async(robots, grippers):
    home_joint_angles = [-0.00297146, -1.27808701, -0.06180186, -2.59758093, -0.01405989, 1.3100147, 0.78735533]
    motion = JointWaypointMotion([JointWaypoint(home_joint_angles)])

    for robot, gripper in zip(robots, grippers):
        gripper.open(0.1)
        robot.recover_from_errors()
        robot.move(motion, asynchronous=True)

    for robot in robots:
        robot.join_motion()

if __name__ == "__main__":
    robot_ip_list = ['172.16.0.2', '172.16.1.2']
    robots_list = []
    grippers_list = []
    for robot_ip in robot_ip_list:
        robot = Robot(robot_ip)
        robot.relative_dynamics_factor = 0.15
        robots_list.append(robot)
        grippers_list.append(Gripper(robot_ip))
        
    move_home_async(robots_list, grippers_list)

Does franky officially support controlling multiple Franka robots from a single host machine?
If yes, what is the recommended approach (e.g., separate threads, processes, or specific API patterns)?
Any guidance or example code for multi-robot control would be greatly appreciated!

Thank you again for your excellent work!

Best regards,

190544560.mp4

[TimSchneider42]

In principle, that should work. To confirm, does the robot not do that when it is not controlled jointly with the other robot?

[SuperFanBin]

Yes, if I use blocking control to move the Franka robotic arm sequentially—one motion at a time instead of moving all arms simultaneously—there will be no issues at all. The code is as follows:

from franky import Robot, Gripper, JointWaypoint, JointWaypointMotion

def move_home(robots, grippers):
    home_joint_angles = [-0.00297146, -1.27808701, -0.06180186, -2.59758093, -0.01405989, 1.3100147, 0.78735533]
    motion = JointWaypointMotion([JointWaypoint(home_joint_angles)])

    for robot, gripper in zip(robots, grippers):
        gripper.open(0.1)
        robot.recover_from_errors()
        robot.move(motion)


if __name__ == "__main__":
    robot_ip_list = ['172.16.0.2', '172.16.1.2']
    robots_list = []
    grippers_list = []
    for robot_ip in robot_ip_list:
        robot = Robot(robot_ip)
        robot.relative_dynamics_factor = 0.15
        robots_list.append(robot)
        grippers_list.append(Gripper(robot_ip))
        
    move_home(robots_list, grippers_list)

[TimSchneider42]

Could you try re-creating the motion object for each arm? I am suspecting that I might be saving some state in the object, causing the two controllers to interfere. Please let me know if that works.

Best,
Tim

[SuperFanBin]

Yes, following your suggestion, the Franka arms are now working properly. Thanks a lot!

[TimSchneider42]

Great! Please leave this issue open, so I remember to fix this bug eventually.