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cycraft

Discussion in 'Commercial Simulators and Peripherie' started by riton, May 19, 2009.

  1. riton

    riton Active Member

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    http://www.youtube.com/watch?v=D4qtxMPbfUk
    What do you think about this construction, this type of simulator?
    sensations are well?

    you think it is interesting to build a simulator of this type (DIY)
  2. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    My Motion Simulator:
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    Movements are not precise and inertia too much to stop the cockpit immediately. As far as i see movements are not even syncron to the game. Just like a big rollercoster, but only for fun it looks ok :)
  3. riton

    riton Active Member

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    the center of rotation is above the head, it 's better for good sensations.
    there is no parasite force
  4. R-eng

    R-eng Member

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    There is a more pro version of this simulator here,

    http://www.simuline.com/product/pro_cycraft.htm

    I feel these simulators are actually capable of far more accurate motions than the frex or joyrider models. The overhead drive system more precisely conforms to the sensors within our auditory and vestibular pathways. This method actually moves all parts of the body in unison to the forces applied. The vertical motions exhibited are because this sim is 3DOF, and has a vertical component just like the FD301/401. It definitely appears stout enough in construction. If it does not move accurately to the video, in my assessment, that is probably due to the software which is arcade like.

    Building a DIY version would require very strong structure, motors and electronic drive modules... $$$. But it could be a very accurate method of simulation.

    Here is a good explanation of this concept they call parasitic
    http://www.simuline.com/library/tech.htm

    R-eng
  5. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    My Motion Simulator:
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    The head with the vestibular system keeps at the near of the pivot and doesn´t move as much as the rest of your body.

    Inertia mass of your head is much more fewer than rest of the body, therefore i see two main disadvantages:

    1) Your legs and torso feel as someone is pulling them away from your heads position.
    2) Strong G-effects appeal to your legs, fewer strong to your torso and only a few to your head with the vestibular system. I could imagine that causes much irritations and not a realistic g-effect in comprehension to real driving.

    Compare it with the following and think of taking a ride on a swing just like everyone of us had done it before in their childhood:
    I remember when i swinged and reached the endpoint of movement, my legs were pulled very strong to the front, and my head kept in place. That behavior feels very unrealistic for a simulator imho.


    I don´t understand the described parasite force physic behind it:
    http://www.simuline.com/product/pro_cycraft.htm

    Can you explain me, why the forces in the initial moment of movement on a simulator with bottom-pivot works to the opposed direction and with a motion simulator with top-pivot goes along the same direction of simulator movement?
  6. egoexpress

    egoexpress Active Member

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    The inner ear controls our sense of angle inclination.

    Imagine our equilibrium organ in a simplified manner (as a ball in a tube):
    ___________________
    |________0_________|
    left------middle------right

    Common simulators with pivot beneath the body do accellerate the head (with equilibrium organ) in the wrong direction.

    Placing the pivot above the head keeps the head to rest in position, and the equilibrium organ does not send false body position signals to our brain.

    I agree that this way is a superior method of simulating g-forces.

    But it is no option for DIY, I guess, as the motor power requirements are very high.

    regards
  7. R-eng

    R-eng Member

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    Well said Egoexpress.

    @ Rayrace,

    Well, what I experienced as a child, and even today, is that my head is connected to my body with a flexible neck. When a rapid movement change happens on my body, my head wants to continue in the direction before the change, because of its mass. Lucky I have a neck to keep it with my body then! :happy:

    Your legs will feel the pressure from the surrounding structure and seat as they press against it during motion changes. They too will be flexible to move if not held in place. When you lay in bed motionless, what do you feel? Gravity via the pressure exerted on your body by the bed. The bed pushes against you as much as you push against the bed...laws of physics.

    Even a tiny change in the position of the head can be sensed very clearly, both by the vestibular pathways and the nerves in the neck and other involved muscles.

    R-eng
  8. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    My Motion Simulator:
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    Why? When my sim moves forward, my head moves to the same direction!
    Or do you mean only the ball in the vestibular system which keeps in place for a short moment due to their mass intertia and... Ups ... * a light comes up *... i understand... :

    Working verstibular system - Pivot-bottom Sim:
    The head moves forward, hairs in the vestibular system are pushed backwards because the vestibular liquid stays in position (inertia) . After a while when the inertia forces are neutralized, the liquid starts moving along the same direction as the head, due to the friction force between liquid and moving vestibular system.

    But i think it is negligible for a Motion sim to prevent such opposed forces! I even claim it is a disadvantage to prevent them, because, in a real moving environments your vestibular system generates the same opposed accelaration signals as in your bottom-pivot sim.

    You start driving and the same biomechanical processes as mentioned above runs.

    It only seems that the visual stimuli threashold exceeds in that situation, so you don´t feel to drive backward. I claim when that vestibular backward signal is missing or very short, for the simple reason that you are sitting in a bottom placed pivot sim, your brain noticed, that there is something wrong. At least at the beginning, after a while your brain adapt to the new sensation of g-force sensoring and you don´t feel the difference. (only assuming!)

    Yes, thats why we need H.A.N.S. and head rests, so that head and rest of the body stay together :)
  9. R-eng

    R-eng Member

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    As I once posted about this subject, as long as the same cause and effect is repeatable on a consistent basis, the mind will adjust to it and consider it valid. That does not make it accurate though!

    When you brake in a car, the head will move forward (relative to the rest of the body) both initially and during the deceleration. This is the negative longitudinal 'G forces. In a bottom pivot simulator, you are pitched forward so that the initial motion (the surge DOF) is for the head to remain stationary (or move backwards relative to the rest of the body), just as you would find in accelerating a car. After the sim moves to its rest brake position (ie. pitched forward), the force of gravity will impart it's effect just as if you were braking a real car.

    In a top pivot sim during braking, it will move backwards both initially and while it assumes the final rest brake position. There are no opposing forces as in the previous bottom pivot model.

    Both can be valid if the sim consistently applies these motions to the forces. The mind will adapt and correlate it as what is expected during such motions. Only one is accurate...the top pivot model, or any other that would apply initial and continuous motion in the same direction.

    R-eng
  10. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    Ok, is see! That principle is easier to understand than i thought at first. Good explanation.

    So, now i think about a way to reduce that negative forces to be more accurat to the real. Finding the balance between speed and accelaration could it be.

    For a breaking simulation the initial movement of the sim accelaration should be very small and before reaching the limit of movement the speed muste be reduced with the same soft decelleration, so that you only feel gravity forces and no false accelaration forces, because they appeal in the wrong direction.

    Also i think in a SCN5 simulator the negative forces doesn´t play the same importance than in a regular bottom-pivot platform design because of the another principle of operation, simulating g-forces by muscle contraction and not by gravity force.

    regards
    René