Control robot from gamepad with SpeedJ or ServoJ

Technical Questions URScript
1

Hey,

I have encountered a problem. If I use the servoj script command and then speedj script command I got polyscope error: “Another thread is controlling the robot”. What is the problem? why can’t I switch from servoj to speedj?

Thanks in Advance,

2

Hi,

i never used a switch to speedj from servoj, but a switch to movel,movep and movej. I think the servoj command is not yet completed as you’re switching. Are you using the optional t param of the speedj command? can you show a minimal example of your code?

3

Yes, that’s right. I have to wait until servoj complete the motion. however I don’t want to wait till the robot stops. for example if I use speedl with specific linear velocity and after that with another speedl command. the arm will complete the first velocity command then stops and after that initiate another velocity command. I want to execute a siries of velocity commands so the arm will execute smooth trajectory. Do you know how can I manage to do that with speedl or any other velocity control method?

Thanks in advance

4

which velocity command is suitable highly depends on your application. If you want a dynamic change of the motion on runtime, servoj is best. If your path is pre-defined and does not have too narrow waypoint distances, i would recommend using movej with high blend settings. Can you describe your application?

1 Like
5

I want to control the robot via logitech gamepad with velocity commands in operational space. I have tried speedl, but I must wait until the arm reaches the defined linear velocity and then stop. after that the arm executes the next velocity command. servoj gets a joints input and I want to send velocity commands.

Thanks for the help.

6

Hi,

interesting task :slight_smile: i would love to try that too…
you can generate a pose and use servoj with the inverse kinematics of that pose:
servoj(get_inverse_kin(targetPose),t=…)
I would try generating waypoints depeding on your analog sticks direction and position.

7

thanks, my problem is that it is not smooth. I can send commands, but it completes the commands one at a time, it makes not a smooth motion. I mean if I give one position commands it stops not smoothly in the end of the motion.

thanks for the support.

8

Hi,

what are your servoj parameters and your target position data update cycle?

9

Hey I have managed to control the arm with gamepad + ros (I will share the code once it will work with ros). However, I need to disable the ros controller first otherwise the controller brings it back to initial position, before the gamepad manipulation. I struggle to disable the controller because once I disable it. the communication drops down.