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Dynamixel AX-12 help

asked 2011-08-12 03:34:22 -0500

Aether robot gravatar image

Hi there.

I'm trying to work with ROS and AX-12 servos on an eeePC. I have the USB2Dynamixel dongle and i can read the states of the 3 servos I have connected by using the ax12_driver_core package, but cant find and way of actually controlling the servos to move. The robotis package has launch files but for the RS series of servos. Any help would be wonderful.

Thank you in advanced. Chris Paton

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Hi Chris--you might want to check out the new dynamixel_motor stack ( which I believe will be replacing ax12_driver_core going forward. (Though Anton can correct me if I am wrong.)
Pi Robot gravatar image Pi Robot  ( 2011-08-12 04:34:28 -0500 )edit

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answered 2011-08-12 04:35:59 -0500

arebgun gravatar image

Both ax12_controller_core and ax12_driver_core packages are deprecated, you should use dynamixel_motor stack instead. Try working through the tutorials and see if they help. If you run into any problems, just update the question and we'll try try to resolve them.

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answered 2011-08-15 01:47:13 -0500

Aether Robotics gravatar image

Works great, thank you, but how would I get it to move 3 servos at once or get one to pan? Is there any example code around or if anyone is willing to share theirs it would be wonderful.

Thank you again for help Chris

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Hi Chris--a while back I wrote a tutorial to do head pointing using the ax12_controller_core package. I have not updated it to use dynamixel_motors instead but it might give you some coding ideas since the topic and service API has not changed. You can find it here:
Pi Robot gravatar image Pi Robot  ( 2011-08-15 06:17:43 -0500 )edit

answered 2011-08-12 03:38:52 -0500

makokal gravatar image

Perhaps you should have a look at the smart_arm_controllers from UA. I have used them before successfully with AX-12 servos. Here is the relevant link

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answered 2011-08-12 05:23:26 -0500

Aether robot gravatar image

thank you, will give that a go now

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answered 2011-08-12 03:50:25 -0500

Aether robot gravatar image

updated 2011-08-16 05:45:22 -0500

mjcarroll gravatar image

tried them, get these errors:

Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://aether-book:32957/


 * /shoulder_tilt_controller/motor_master/init
 * /rosdistro
 * /shoulder_pan_controller/controller/package
 * /shoulder_pan_controller/joint_name
 * /shoulder_tilt_controller/joint_speed
 * /shoulder_pan_controller/joint_speed
 * /shoulder_tilt_controller/motor_slave/id
 * /shoulder_pan_controller/motor/id
 * /shoulder_pan_controller/controller/module
 * /shoulder_tilt_controller/controller/module
 * /shoulder_tilt_controller/motor_master/id
 * /shoulder_tilt_controller/controller/package
 * /rosversion
 * /shoulder_tilt_controller/controller/type
 * /shoulder_tilt_controller/joint_name
 * /shoulder_tilt_controller/motor_master/max
 * /shoulder_pan_controller/motor/min
 * /shoulder_pan_controller/controller/type
 * /shoulder_pan_controller/motor/max
 * /shoulder_pan_controller/motor/init
 * /shoulder_tilt_controller/motor_master/min

    smart_arm_controller_spawner (ax12_controller_core/


core service [/rosout] found
process[smart_arm_controller_spawner-1]: started with pid [4726]
[INFO] [WallTime: 1313164188.816477] ttyUSB0 controller_spawner: waiting for controller_manager to startup in global namespace...
[INFO] [WallTime: 1313164188.874621] ttyUSB0 controller_spawner: All services are up, spawning controllers...
No handlers could be found for logger "rosout"
[ERROR] [WallTime: 1313164188.918949] Cannot find controller module. Unable to start controller joint_position_controller
No module named joint_position_controller
[ERROR] [WallTime: 1313164188.955237] Cannot find controller module. Unable to start controller joint_position_controller_dual_motor
No module named joint_position_controller_dual_motor
[ERROR] [WallTime: 1313164188.962476] [elbow_tilt_controller] configuration error: could not find controller parameters on parameter server
[smart_arm_controller_spawner-1] process has died [pid 4726, exit code 1].
log files: /home/aether/.ros/log/612bfeb2-c4f2-11e0-95eb-00261882a7d2/smart_arm_controller_spawner-1*.log
all processes on machine have died, roslaunch will exit
shutting down processing monitor...
... shutting down processing monitor complete
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Asked: 2011-08-12 03:34:22 -0500

Seen: 2,009 times

Last updated: Aug 16 '11