• July 21, 2014 at 19:28 #6018

    Driving a robot arm from the keyboard is tricky.

    Forward kinematics work just fine – move the shoulder and you know where the finger tip goes.

    Inverse kinematics are junk – if you move the finger tip and try to figure out where the rest of the arm should be there are lots of special cases. Sometimes the arm tries to magically flip over.

    Rather than try to solve a lot of problems with a klunky, hard to use interface I decided to get some potentiometers and build a little joystick instead. I’ve traded a lot of hard to solve software problems for less hard to solve hardware problems.

    http://hackaday.io/project/945/log/5264

    Maybe one day I’ll be able to combine the joystick and the arm into a single device that can detect collisions and is human-safe. Until then I have to work up in stages.

    So now the challenge is making a few mechanical pieces. Anyone know how to make an L-bracket?

    November 5, 2014 at 05:28 #6740

    Did a google search and hope you’ve found or run across Steven Lu’s:

    http://www.youtube.com/watch?v=HRU1Tlv0GtQ

    in particular the credits at the front regarding Rick Parent and his book: Computer animation? ($20 used from on-line textbook store) and help from Alexandros Dermanakis.

    Also the youtube lecture from QUeensland school on kinematics and inverse kinematics:

    http://www.youtube.com/watch?v=VjsuBT4Npvk

    Let me know.
    Carl Nelson

    November 5, 2014 at 17:44 #6741

    My math ends in high school. Most of this is way over my head.

    Right now my approach is to build a scale model of the arm that has potentiometers and then guide it by hand. Dynamic? No. Easy? Yes. Good place to start? …why not.

    Are you willing to tackle the challenge of doing the IK? Let me know how I can help.

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