Dobot Magician -Rotation axis of suction cup / gripper not responding


#1

Hello everybody,
I am a new Dobot Magician owner purchased from Dobot Distributor in Germany.
We are looking forward to the introduction of the M1, which could be a great help in our production of sensors. So we thought it best to test the quality of Dobot products and the software by buying a Dobot Magician first.

The first impression of the Magician was great and we succeeded fast to write our first applications.
However, we encountered three problems, which I have posted under:
-Bluetooth not visible or not working
-Rotation axis of suction cup / gripper not responding
-Mac OS error -67062 with Mac OS 10.11.6

Firmware and Robot Studio (Win10) are latest.
All axises are responding correctly to any commands from the Notebook. Only the rotation-axis does not respond. The software “simulates” movement by changing values of the rotation axis correspondingly to the commands, but no sound or movement is recognisible from the motor of the Dobot. Connector was plugged to GPI-3.

Any suggestions? Do we have to position the suction-cup or gripper to a predefined angle (as with the other axises when initializing the Dobot?

Thank you in advance

Rudolf


#2

I am encountering a similar problem when running from Python.
(Product: Dobot Magician, using dll downloaded from dobot.cc, labelled Dobot DemoV2.0)

The Suction Cup / Gripper will rotate anti-clockwise, but will not rotate back clockwise.

Example Code:

dType.SetPTPCmd(api, dType.PTPMode.PTPMOVLXYZMode, 130, 0, 0, 0, 1) dType.SetEndEffectorGripper(api,1,0,1) #open dType.SetPTPCmd(api, dType.PTPMode.PTPMOVLXYZMode, 130, 0, -28, **45**, 1) #go down and rotate 45 degree (rotates correctly) dType.SetEndEffectorGripper(api,1,1,1) #close time.sleep(2) #wait to pick up item before rising dType.SetPTPCmd(api, dType.PTPMode.PTPMOVLXYZMode, 130, 0, 20, **0**, 1) #get up and rotate back to 0 degree (not working correctly. does NOT rotate) time.sleep(1)

Rotating anti-clockwise works, but Rotating clockwise does not work via API
The code above results in the arm correctly opening, rotating 45 degrees and picking up the object (correctly)
BUT when it comes back up, it does not rotate back to 0 degrees as expected.

Nothing wrong with servo, because it works when using Dobot Studio
It works (rotates both directions) when running as a playback from Dobot Studio. However, when run from the dll using the API, it only rotates in one direction. (It only rotates back to 0 when a Home All is executed)

Question
Is there any way that I can trigger the correct clockwise rotation of the Suction Cup / Gripper from code/API?

Thank you.


#3

Updated. Managed to get the rotation resolved.
Used dType.PTPMode.PTPMOVJXYZMode instead.

dType.SetPTPCmd(api, dType.PTPMode.**PTPMOVJXYZMode**, 130, 0, 0, 0, 1) dType.SetEndEffectorGripper(api,1,0,1) #open dType.SetPTPCmd(api, dType.PTPMode.**PTPMOVJXYZMode**, 130, 0, -28, 45 , 1) #go down and rotate 45 degree (rotates correctly) dType.SetEndEffectorGripper(api,1,1,1) #close time.sleep(4) #wait to pick up item before rising dType.SetPTPCmd(api, dType.PTPMode.**PTPMOVJXYZMode**, 130, 0, 0, 0 , 1) #This works now!

Hope it helps!


Edited: The User Manual has some details on the different movement types: JUMP: From point A to point B, the trajectory is shown below, the end effector will lift upwards by amount of Height (in mm) and move horizontally to a point that is above B by Height and then move down to Point B.

MOVJ : Joint movements. From point A to point B, each joint will run from initial angle to its
target angle, regardless of the trajectory. The motion time for all joints are the same which means
all joints will start and finish at the same time.

MOVL: The joints will cooperate in order to perform a line trajectory from point A to point B.


#4

“-Bluetooth not visible or not working”
Do all the lights of the bluetooth module light up as the demo video shows?

"-Rotation axis of suction cup / gripper not responding’
Could you send me a video to check this?

“-Mac OS error -67062 with Mac OS 10.11.6”
We released a new version studioV1.4.0 for mac today, please download and check it again.


#5

Hello Jim, hello Eric,

thank you Jim for posting your script and your solution to your rotation problem.
I run the script on my robot. It moved as expected, but still no rotation visible.

@Eric: I will send you a video in the next days (currently quite busy).
Thank you for Version 1.4 - got it running on my Mac now.

1 1/2 down 1 1/2 to go ;-).

tks

Rudolf


#6

Hello Rudolf @SAGDobot ,

when you said you plugged the rotating servo to GP3, did you plug it to the port labelled 1 on the arm?
Maybe can double check, because GP3 is actually the first port nearest to the rotating servo, and NOT the one labelled 3.

If all the connections are correct, maybe one other troubleshooting step is to connect using the user friendly Dobot Studio and to use the GUI to set the rotating servo to rotate (teaching and playback > then set R to any non zero value). If it works in Dobot Studio, then the issue may probably be in the python code. If it does not work even in Dobot Studio, there may be an issue with the way your wires are connected. (in that scenario, a photo may be useful for others to try to help to troubleshoot)

Hope it helps. :slight_smile:


J4 axis does not turn
#7

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#8

Thanks a lot jlim, I used to have the same problem and your answer solved it perfectly !