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Thread: Parallel Leg Mechanism Design

  1. Re: Parallel Leg Mechanism Design

    I am thinking the benefit of linear actuator vs servo vs hydraulic.

    For human size robot I think it is hard to create a very big servo that can create enough torque. Linear actuator is much stronger. Though slower maybe.

    For hydraulic, can it be that a human size robot will have one pumping engine that will power all the hydraulic actuator on the robot. This way having an extra dof will be more cost efficient.

    Just some thought.

  2. Re: Parallel Leg Mechanism Design

    Here's a test of a PLM setup for my sons light weight robot. Has a Robonova body for now.
    [ame="http://www.youtube.com/watch?v=YJlL55KlMKk"]YouTube - Parallel Leg test.3gp[/ame]
    Last edited by TOhm; 11-14-2010 at 10:04 PM. Reason: Couldn't get video to work. Newbie mistake

  3. #73
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    Re: Parallel Leg Mechanism Design

    I like this design. Only two servos in each leg!

  4. Re: Parallel Leg Mechanism Design

    Take a look at the second picture in the thread. Notice the springs connecting the front and rear linkages.

    You can design a fourbar mechanism using springs that can compensate for load at almost any position through the rotation of the linkages. Many lamps (dentist offices) have this kind of design which allows you to reposition the lamp, but have it stay in place without having to tighten or loosen any parts.

    Why add extra servo's when you can use springs to compensate for the load instead.

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    Re: Parallel Leg Mechanism Design

    Here are some pictures of my mech. It was on the shelf for a while until this thread came along. It has a locked knee but this setup has definitely increased stability and reduced backlash. I plan to make some brackets for a two servo pivoting knee version. With the current configuration I can use the same walking gate as before. Video below is pre PLM but demonstrates the walking gate.


    [ame="http://www.youtube.com/watch?v=G0Dk0rUvxIk"]YouTube - bioloid biped using arbotix controller - 1[/ame]








    Last edited by muc; 01-10-2011 at 02:22 PM.

  6. #76
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    Re: Parallel Leg Mechanism Design

    Very cool. This would make a great biped platform for Mech Warfare. Great job on the wiring too btw.
    Last edited by billyzelsnack; 01-05-2011 at 10:58 AM.

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    Re: Parallel Leg Mechanism Design

    Nice! Bring it to the robot meeting this month!
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    Re: Parallel Leg Mechanism Design

    I love the craftsmanship that you've done with your mech much; very nice details w/the wiring alone! Something I'll keep in mind with whatever bot(s) I do.

    Paul

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    Re: Parallel Leg Mechanism Design

    thanks for the nice comments

    Here is a PLM leg I've wanted to try. I don't have the parts to build a second yet. Hopefully in the next week or two I can get a second put together and test things. Motion is somewhat limited but should work fine for mech-warfare.










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    Re: Parallel Leg Mechanism Design

    Hi Tyberius
    That's a very good post. I want to design a leg too.
    You mentioned that PLM is much smoother when it is walking. But do you think it is only mainly because of the parallel linkages binding the joints into "one" leg? With normally mechanism, better control should do the same.
    I guess what I am saying is: on the "smoother" part, PLM did something mechanically that could be done by software in the normally mechanism.
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