Change motion from rotation to linear

Home Forum Stewart/Gough Platforms Change motion from rotation to linear

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    I got a good start, I think. Some of the confusion was understanding the terminology. These pictures are what I think I discerned from my observations and assumptions.

    I think I sorted out some of the configuration:
    // measurements based on computer model of robot (in cm)
    #define NUM_TOOLS (6)
    #define BICEP_LENGTH ( 5.000)
    #define FOREARM_LENGTH (50.0)

    // top center to wrist hole (relative): X7.635 Y+/-0.553 Z0.87
    #define T2W_X ( 15.5)
    #define T2W_Y ( 4.5)
    #define T2W_Z (-1.0)
    // base center to shoulder hole (relative): X8.093 Y+/-2.15 Z7.831
    #define B2S_X ( 10.5)
    #define B2S_Y ( 14.0)
    #define B2S_Z ( 1.0)

    The next thing I need to sort out is how to change the motion from rotation to to linear.

    From looking at the code, it seems like I need to get rid of the bicep. Looks like in update_ik I need to get rid of update_shoulder_angles. Should be that a lot of the code should get a lot simpler, right?

    Anyway, I am done for the day. Thanks!


    Hello Kevin,
    I’d like to build a linear hexapod as well. Did you get any further? As seen on youtube Dan already built a linear actuated hexapod ( but I don’t think the code is available in the git.
    My understanding of Dans code is the same, I guess we could change it and it would get ‘shorter’ .. I will try to figure out how … (Don’t know if I am capable of doing it due to my limited programming knowledge)


    The number one thing that stopped me from making more stewart platforms like this is that the linear actuators don’t have linear position sensors. Without that I don’t feel I can safely move the system around. Yes, there are less good ways of doing things – like limit switches and dead reckoning. I’m want reliable results.


    The Actuonix actuators which are used quite often (little bit pricey) have a potentiometer ( Feedback Potentiometer: 2.75 kOhm/mm ± 30%, 1% linearity)
    Do you think this will be sufficient ?
    My plan is to use t5 lead screw actuators nema 11 homebrew design.

    There is an other code source which looks very interesting for building these type of robots

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