Achieving Interas movement fluidity in the Intera SDK.


CSIC
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Is there any tips and advice on improving sawyers movements using the SDK? Intera has some nice movements that make the robot look much more attractive than I've managed to achieve with the SDK.

Is it purely using the Motion Waypoint system? I'm currently using that for cartisean based movements but I get a lot of erros with "Cartisean Path not Found" when it managed such a movement fine in the same joint positions.

Any advice is welcome.

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  • 2 weeks later...

Hello CSIC,

We are using the "Joint control modes", mainly the "joint position control" (using the set_joint_positions() method of the Limb() class) and the "joint trajectory control" (using the set_joint_trajectory() method of the Limb() class).
Basically, when we have a cartesian pose, we convert it to a set of joint angles using the ik_request() method of the Limb(). Then we send this joint angle command using the set_joint_positions() method. We send these joint commands at a rate of 100Hz, and we try to adapt the joint velocity using the set_joint_position_speed() method of Limb(). For now it seems to work.

Using the Joint trajectory control, since you need to provide the velocity and acceleration of the joints for every command you send, we had to compute the velocity and acceleration of the robot ourselves (in our case, with our own model of the robot because we wanted to do it anyway). The joint names, angles, velocities and acceleration are then sent at a rate of 500Hz and the trajectory is quite smooth (we tried 100Hz and 800Hz too).

In our case we are trying to make the Sawyer follow a trajectory. I guess if you want a "point-to-point" motion, you could also use theses methods (joint commands directly) to achieve your motion.

Best regards,

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  • 2 weeks later...

Do you have any code you could possibly share? Especially how you go around calculating velocity and acceleration. I've avoided using the joint trajectory method as I don't have the time to implement it, I've managed so far with just the ik and set_joint_positions and the Motion Waypoint system.

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