Reaching a target point: Bridges and Scaffolds

In our first experiments we conceived a Lego plate affixed to a table (fig. 2.14) and evolved 2D structures to reach a target point, using as fitness function a normalized distance to the target point,

$$Nd(S,T)=1-\frac{d(S,T)}{d(0,T)}$$ (2.12)

  

Figure 2.14: Lego bridge experimental setup: The structure starts on a Lego plate affixed to a table and has to reach a target point supporting its own weight.

(where S is the structure, T the target point and d the euclidean distance).

  

Figure 2.15: The Lego bridge defined by the scheme of fig. 2.2, built on our lab table.

With a target point T located horizontally and away from the plate we generated a Lego bridge (figs. 2.2 and 2.15). Moving T to a remote position we obtained the ``long bridge'' (fig. 2.20), and putting T below we generated a descending structure, a ``scaffold'' (fig. 2.16).

  

Figure 2.16: Scaffold.