NetLogo User Community Models
by James Steiner (Submitted: 07/06/2005)
WHAT IS IT?
This model is some kind of physics / machine / links simulation.
It has a nifty drag-n-drop interface for positioning the elements on the work surface. The "selected" element is circled, and can be changed with the property buttons.
When I told someone what I was doing, they asked me "what integrator are you using?" I said, "huh?" Then they started talking about integrals and derivitives and other calculus-y stuff. Well, there is no caculus in this. There is math, there is trigonometry. All very simple.
This model is a great example of "emergent" behavior. All of the cool things that the levers do emerged from the simple code that runs them. This code is mostly concerned with each lever trying rather simple-mindedly to keep its attachment points (hooks) attached to its neighbor's attachement points. Swinging, crumpling, pushing and pulling all emerged from that.
I'm not really sure why it works, but it does. Each element (lever) has two hooks. The levers want to be centered bewteen attached levers. Likewise, they want to point to both attached hooks.
There's to0 much sag. I'm not sure how to keep the levers from seperating. That may just be a limitation of this method.
I had some goals in mind when I started. I wanted the elements to exhibit these behaviors.
1. "fixed" nodes spin in response to movement of the chain.
Gravity affects things a great deal.
New: based on a modification sent to me by Seth Tisue, I added sound to this version.
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