ROS

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  • #453 Quote
    David Wright
    Participant

    Hello all,
    I am interested in testing my (soon to be built built) Thor arm’s capabilities. To do this, I wanted to be able to incorporate it with the Robotic Operating System, the most widely used open-source robotics platform. I have found a description package for Thor on the ROS pages, so clearly prior Thor builders have tried ROS. Is that anyone here? ;
    I will document my experiments with integrating ROS and Thor as they progress

    #737 Quote
    Kevin Friesth
    Participant

    David,
    Your best bet for use with ROS would be to go in a different direction for the interface for the current interface concept , for simplicity and ability to reuse the setup for any robotic arm would be to use a i2c stepper controller with gpio for input from an encoder for high resolution feedback positioning.
    I would recommend the PCA9629W and then size your drivers to match the stepper motor requirements, using this arrangement will allow stepper motor and an encoder as a positioning sensor for high precision movements allowing all movement and sensor basis as an offloading design, will allow a flexibility for the controller for say a simple Raspberry PI 3 to operate in a headless mode but allow say opencv visual interfacing as a later add-on without causing a major redesign.
    Cheers,
    Kevin

    BTW a quick reference if you wanted to make your own encoder and print the parts… ;http://meetjanez.splet.arnes.si/2015/10/03/cheap-easy-diy-optical-encoder-attiny-3d-printing/

    #739 Quote
    Kevin Friesth
    Participant

    BTW this is a cheaper method than the one being used currently and will allow for as many axis/grippers (yes fingers independently too as it can have 1mbps data) as you want, even run a pair or arms if you wanted from the same controller them to work together and still run on a Rasp III and still able to do opencv visual…just saying
    Best Regards,
    Kevin

    #741 Quote
    Oliver Schumacher
    Participant

    Hi David,
    can you link Thor ros packages?I am working on ROS intigration as well. And i actually use Angels Hardware.I do not see a prob to do so.But for sure to implement thor in ros there are some custom ROS node needed. ;I am working in ROS indego. And have put the Ardurino board to an Intel edison via serial line.On Intel Edison i have ros runnning. On Ardurino GRBL FW.
    Im working on URDF config actually. To simulate Thor in ROS. The will programm the needed nodes to attach ROS to grbl.

    CU Oliver

    #743 Quote
    David Wright
    Participant

    Thank you very much for the thoughts on control electronics. I am interested in seeing how the Pi3 with i2C would work for control, as you mentioned. I will look into those encoders as well for some of the closed-loop control.
    This is the URDF I had found for the Thor arm. I don’t know how accurate or complete it is, but it looks like someone else has started on this road before: ;https://github.com/b-adkins/thor_arm_description
    The same user put together a MoveIt package I using that URDF as well: ;https://github.com/b-adkins/thor_arm_moveit
    I will let you know what I find for ROS integration and controlling Thor from a Pi!
    David

    #745 Quote
    Abhinav Gandhi
    Participant

    Hello David!

    Do you have any updates on the ROS implementation for Thor? I am thinking of working on the same soon.

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