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Human powered hydraulic exoskeleton

  1. Jun 13, 2015 #1
    I want some suggestion about designing a hydraulic exoskeleton whose input would be the kinetic motion of the body....the force exerted by body would be used to give an input to the hydraulic system which would inturn give a larger force as output in real time.for example an arm with exoskeleton is flexed at elbow joint by a force of 20 kg these kgs would be the input force for the system which in turn would move the exoskeletal joint with a large force let it be 80kgs
     
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  3. Jun 13, 2015 #2

    Borg

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  4. Jun 13, 2015 #3
  5. Jun 13, 2015 #4
    There is very little on available on this topic...yes i have searched for it
     
  6. Jun 13, 2015 #5

    Borg

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    This is a broad topic. I'm not an expert on hydraulics but the answers could range from "do lots of reading" to the specifics of designing various motors. It helps if you explain what you've done and where you're stuck. It makes it easier for others to help you.
    Also, take a look at the list of similar discussions at the bottom of the page. You might get some ideas from there as well.
     
  7. Jun 13, 2015 #6
    Yes very broad topic.

    For a design, one has to begin with a concept, which can range from that featured in the wiki article from Borg, where the system is attached next to the human body, to something such as portrayed in the movies, such as the assisted freight forklift system used by Sigourney Weaver in Alien, where the user can just enter into the machine and easily activate; or as elaborate as that from the movie Ativar. You will need to be familiar with several disciplines, as shown in the Wiki.

    Start.
    From the concept, one can determine possible dimensions of the machine and its components, and possible range of movements.
    From there, forces, torques, stresses and strains at the various joints and members.
    Next, a selection of the components, which would include the actuators, sensors, power supply, materials for the members, etc.
    Keep a running bill of materials into which one adds the component, dimensions, material and amount, cost of fabrication, time for assembly,etc
    Additional list items ........
    Go to start if something needs adjustment, expect to do that several times.

    Once done, select a paint color, logo. ( you could do this at just about any time but it will change )

    End:

    Present it to the world.
    And charge a lot.

    Don't expect to do it all in one weekend.
     
  8. Jun 13, 2015 #7
     
  9. Jun 13, 2015 #8
    The suggestion i was asking is about the design of the system converting kinetic motion of body into the motion of the hyraulic cylinder........the exoskeleton donot need external power source its powered from the motion of the human body......mechanically.....what type of system would u suggest to be the best
     
  10. Jun 13, 2015 #9

    Borg

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    No outside power source? And you want to turn 20 units of force into 80? Good luck with that.
    You might want to read up on units of force while you're at it. Kilograms isn't in the list.
     
  11. Jun 13, 2015 #10
     
  12. Jun 13, 2015 #11
     
  13. Jun 13, 2015 #12
    Tell me how much force u exert on a human operated hydraulic jack to lift a truck.....and kilogram force is used as unit of force....
     
  14. Jun 13, 2015 #13

    Borg

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    The abbreviation for that is kgf not the kg that you used.

    You still haven't said what you've tried or where you're stuck. Honestly, PF gets plently of questions like this where the poster asks questions like this. Unless you're willing to provide more information, it's unlikely that you'll get much help. It's more likely that an administrator will stroll by and lock the thread.
     
  15. Jun 13, 2015 #14
    You are the one with the idea, so you must have some beginning framework in mind and what you hope to accomplish.

    The work to lift 80 kg ( as you previously mentioned ) has to come from somewhere, and if you are using the human body as the power source, then you will expend just as much energy with or without an "exoskeleton".

    Using a mechanical advantage device, such as a jack, becomes a tradeoff between how much can lifted and the amount ( distance ) of lift. The distance in stroke you provide to the jack lever, if you had not noticed, is much greater than the distance the weight travels. Nevertheless, the amount of work you provided is the same as the gain in potential energy of the weight.

    I have to agree with Borg's previous post.
    It is fun to have a guessing game when playing 20 Questions, but I do think you want to be taken more seriously than that.
     
  16. Jun 13, 2015 #15
    the problem i'm seeing with this concept is not how to increase the force put into the exoskeleton but how you protect the user from the increased force output.

    if the exoskeleton adds 4X's the force how will the user be protected from the results. like bending the hip and it wants to move 4X's as hard in the direction of travel which needs 4X's as much force to stop moving if its not regulated the user could be subjected to some pretty nasty forces. where as if the unit is not a direct drive. sort of like the one in aliens a big biped forklift then you would be using motors or engines to create the strength and sensors to control the movement this removes the user from the forces being created. direct drive can assist movement but is limited in how much it can increase the force the user is exposed to.
     
  17. Jun 13, 2015 #16
    but lets go on another tangent: say what you want to do is soak up wasted energy and use it. sort of like the energy each step creates when you plant your foot and you sponge up that energy and use it to run something else like a hip joint piston. you could reduce the amount of effort needed for forward motion by a fairly equal amount as the amount of energy soaked up by each foot planting as you walk. the issue is as much as you gain with the device.it will be reduced by the amount of extra weight you need to carry to create the assisted motion.
     
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